Imbibing process for contact lens surface modification

ABSTRACT

Medical devices having a wettable, biocompatible surface are described herein. Processes for producing such devices are also described.

FIELD OF THE DISCLOSURE

The present invention generally relates to medical devices, particularlycontact lenses, having a wettable, biocompatible surface and methods ofproducing such devices.

BACKGROUND

Siloxanes are commonly included in contact lenses to improve theiroxygen permeability. However, the inclusion of siloxanes can have adetrimental effect on the wettability or hydrophilicity of the lens. Onesuitable approach to overcome this issue is to coat or modify thecontact lens surface, preferably with a biocompatible material.

Oxygen permeability of hydrophilic contact lens formulations can beimproved, for example, by adding various silicon- andfluorine-containing hydrophobic monomers. Such modifications, however,may come at the expense of lens wettability and biocompatibility; forinstance, materials exhibiting high gas permeabilities due to theinclusion of high levels of silicon or other strongly hydrophobicmonomers frequently exhibit reduced wetting characteristics. This canlead to various problems ranging from poor lens movement on the eye,increased fouling due to lipid, protein, and/or biomolecule adherence tothe lens surface, and adhesion of the lens to the eye. These and otherissues can be remedied by providing a surface modification that makesthe lens surface considerably more wettable.

Various techniques for improving the hydrophilicity of contact lenseshave been disclosed, many of which involve a plasma treatment step. Itwould be desirable to have a surface modification process that did notrequire a separate plasma unit operation, as these techniques can behighly variable, costly, and inconvenient.

In general, various surface properties of materials, such asbioactivity, chemical reactivity, gas permeability, and wettability, canbe improved by polymeric surface modifications. Other desirable featuresthat can be enhanced or improved by surface modifications includeadhesion, biocompatibility, liquid or stain resistance, lubricity,protein resistance, anti-reflective behavior, selective binding ofbiomolecules, and wear resistance. Although some methods of surfacemodification of polymers are known, it would be useful to provideimproved surface modifications and processes for preparing the same.

SUMMARY OF THE DISCLOSURE

Among the various aspects of the present disclosure is the provision ofa process for modifying the surface of a silicon-containing polymer.

Briefly, therefore, the present disclosure is directed to a process formodifying the surface of a silicon-containing polymer, the processcomprising the steps of: imbibing a zwitterionic monomer or a freeradical initiator into a silicon-containing polymer in an imbibingmixture comprising the silicon-containing polymer, at least one of thezwitterionic monomer and the free radical initiator, and a solventsystem; and polymerizing the zwitterionic monomer to modify the surfaceof the silicon-containing polymer with a zwitterionic polymer in apolymerization reaction mixture, the polymerization reaction mixturecomprising the imbibed silicon-containing polymer, a solvent system andthe zwitterionic monomer or the free radical initiator, thepolymerization reaction mixture having a composition that differs fromthe composition of the imbibing mixture.

Another aspect of the disclosure is directed to a process for modifyingthe surface of a silicon-containing polymer, the process comprising thesteps of: imbibing a zwitterionic monomer into a silicon-containingpolymer in an imbibing mixture comprising the silicon-containingpolymer, the zwitterionic monomer, and a solvent system; andpolymerizing the zwitterionic monomer to modify the surface of thesilicon-containing polymer with a zwitterionic polymer in apolymerization reaction mixture comprising the imbibedsilicon-containing polymer, a free radical initiator and a solventsystem wherein the polymerization reaction mixture has a compositionthat differs from the composition of the imbibing mixture.

Yet another aspect of the disclosure is directed to an article formed bythe processes described herein. In one embodiment, the article is acontact lens.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-3 are images depicting various contact lenses stained with eosinand analyzed with EDS to show the boundaries for the region containing asurface modification as described in Example 9.

FIG. 4 is a plot of Si (silicon) and S (sulfur) as a function of depthfrom the surface of a contact lens having a surface modification asdescribed in Example 9.

FIG. 5 is a plot showing the concentration of silicon (Si) and sulfur(S) as a function of depth from the surface of a contact lens having asurface modification as described in Example 22.

FIG. 6 is a plot showing the concentration of quaternary nitrogen (N1s)as a function of depth from the surface of a contact lens having asurface modification as described in Example 22.

ABBREVIATIONS AND DEFINITIONS

The following definitions and methods are provided to better define thepresent disclosure and to guide those of ordinary skill in the art inthe practice of the subject matter of the present disclosure. Unlessotherwise noted, terms are to be understood according to conventionalusage by those of ordinary skill in the relevant art.

When introducing elements of the present invention or the preferredembodiment(s) thereof, the articles “a,” “an,” “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising,” “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

Aliphatic: unless otherwise indicated, “aliphatic” or “aliphatic group”means an optionally substituted, non-aromatic hydrocarbon moiety. Themoiety may be, for example, linear, branched, or cyclic (e.g., mono orpolycyclic such as fused, bridging, or spiro-fused polycyclic), or acombination thereof. Unless otherwise specified, aliphatic groupscontain 1-20 carbon atoms.

Alkyl: unless otherwise indicated, the alkyl groups described herein arepreferably lower alkyl containing from one to eight carbon atoms in theprincipal chain and up to 20 carbon atoms. They may be linear, branchedor cyclic and include methyl, ethyl, propyl, butyl, hexyl and the like.

Amino: unless otherwise indicated, the term “amino” as used herein aloneor as part of another group denotes the moiety —NR¹R² wherein R¹, and R²are independently hydrogen, hydrocarbyl, substituted hydrocarbyl orheterocyclo.

Ammonium: unless otherwise indicated, the term “ammonium” as used hereinalone or as part of another group denotes the moiety —N⁺R¹R²R³ whereinR¹, R² and R³ are independently hydrogen, hydrocarbyl, substitutedhydrocarbyl or heterocyclo.

Amide or Amido: unless otherwise indicated, the “amide” or “amido”moieties represent a group of the formula —CONR¹R² wherein R¹ and R² areas defined in connection with the term “amino.” “Substituted amide,” forexample, refers to a group of the formula —CONR¹R² wherein at least oneof R¹ and R² are other than hydrogen. “Unsubstituted amido,” forexample, refers to a group of the formula —CONR¹R², wherein R¹ and R²are each hydrogen.

Anionic Monomer, Anionic Monomeric Unit or Anionic Repeat Unit: unlessotherwise indicated, an “anionic monomer,” “anionic monomeric unit” or“anionic repeat unit” is a monomer or monomeric unit bearing an anion orother anionic species, e.g., a group that is present in a negativelycharged state or in a non-charged state, but in the non-charged state iscapable of becoming negatively charged, e.g., upon removal of anelectrophile (e.g., a proton (H+), for example in a pH dependent manner)or a protecting group (e.g., a carboxylic acid ester), or the additionof a nucleophile. In certain instances, the group is substantiallynegatively charged at an approximately physiological pH but undergoesprotonation and becomes substantially neutral at a weakly acidic pH. Thenon-limiting examples of such groups include carboxyl groups, barbituricacid and derivatives thereof, xanthine and derivatives thereof, boronicacids, phosphinic acids, phosphonic acids, sulfinic acids, sulfonicacids, phosphates, and sulfonamides.

Anionic species or Anionic moiety: unless otherwise indicated, an“Anionic species” or an “Anionic moiety” is a group, residue or moleculethat is present in a negatively charged or non-charged state, but in thenon-charged state is capable of becoming negatively charged, e.g., uponremoval of an electrophile (e.g., a proton (H+), for example in a pHdependent manner) or other protecting group (e.g., a carboxylic acidester), or the addition of a nucleophile. In certain instances, thegroup, residue or molecule is substantially negatively charged at anapproximately physiological pH but undergoes protonation and becomessubstantially neutral at a weakly acidic pH.

Antimicrobial: unless otherwise indicated, “antimicrobial” refers tomolecules and/or compositions that kill (i.e., microbicidal), inhibitthe growth of (i.e., microbistatic), and/or prevent fouling by,microorganisms including bacteria, yeast, fungi, mycoplasma, viruses orvirus infected cells, and/or protozoa. Antimicrobial activity withrespect to bacteria may be quantified, for example, using a standardassay. In one such assay, samples may be pre-incubated with 50% fetalbovine serum for 18-20 hours at 120 RPM at 37° C. Followingpre-incubation, samples are placed in Staphylococcus aureus (S. aureus,ATCC 25923) which has been diluted from an overnight culture to aplanktonic concentration of 1−3×10⁵ CFU/mL in 1% tryptone soy broth(TSB) diluted in 1×PBS or other suitable media. Samples are incubatedwith bacteria for 24-26 hrs with agitation (120 rpm) at 37° C. Theconcentration of TSB or other media can vary with the organism beingused. After incubation, the samples are placed in 3 mL PBS for 5 min at240 RPM at 37° C. to remove bacteria not tightly attached to thematerial. Then, accumulated bacteria on materials are removed bysonication in a new solution of PBS and the total number of bacterialcells is quantified through dilution plating. Preferably at least a 1,2, 3 or 4 log reduction in bacterial count occurs relative tocolonization on a reference substrate, that is, the same or an otherwisefunctionally equivalent substrate lacking the non-fouling polymer layer.A surface that has a lower bacterial count on it than the referencesubstrate may be said to reduce microbial colonization.

Aryl: unless otherwise indicated, the term “aryl” or “aryl group” refersto optionally substituted monocyclic, bicyclic, and tricyclic ringsystems having a total of five to fourteen ring members, wherein atleast one ring in the system is aromatic and wherein each ring in thesystem contains three to seven ring members. The terms “aryl” or “ar” asused herein alone or as part of another group denote optionallysubstituted homocyclic aromatic groups, preferably monocyclic orbicyclic groups containing from 6 to 12 carbons in the ring portion,such as phenyl, biphenyl, naphthyl, substituted phenyl, substitutedbiphenyl or substituted naphthyl. Phenyl and substituted phenyl are themore preferred aryl.

Attached: unless otherwise indicated, two moieties or compounds are“attached” if they are held together by any interaction including, byway of example, one or more covalent bonds, one or more non-covalentinteractions (e.g., hydrogen bonds, ionic bonds, static forces, van derWaals interactions, combinations thereof, or the like), or a combinationthereof.

Biocompatibility: unless otherwise indicated, “biocompatibility” is theability of a material to perform with an appropriate host response in aspecific situation. This can be evaluated using International StandardISO 10993. Biocompatible compositions described herein are preferablysubstantially non-toxic.

Block Copolymer: unless otherwise indicated, a “block copolymer”comprises two or more homopolymer or copolymer subunits linked bycovalent bonds. Block copolymers with two or three distinct blocks arecalled diblock copolymers and triblock copolymers, respectively. Aschematic generalization of a diblock copolymer is represented by theformula [A_(a)B_(b)C_(c) . . . ]_(m)−[X_(x)Y_(y)Z_(z) . . . ]_(n),wherein each letter stands for a constitutional or monomeric unit, andwherein each subscript to a constitutional unit represents the molefraction of that unit in the particular block, the three dots indicatethat there may be more (there may also be fewer) constitutional units ineach block and m and n indicate the molecular weight of each block inthe diblock copolymer. As suggested by the schematic, in some instances,the number and the nature of each constitutional unit is separatelycontrolled for each block. The schematic is not meant and should not beconstrued to infer any relationship whatsoever between the number ofconstitutional units or the number of different types of constitutionalunits in each of the blocks. Nor is the schematic meant to describe anyparticular number or arrangement of the constitutional units within aparticular block. In each block the constitutional units may be disposedin a purely random, an alternating random, a regular alternating, aregular block or a random block configuration unless expressly stated tobe otherwise. A purely random configuration, for example, may have thenon-limiting form: X—X—Y—Z—X—Y—Y—Z—Y—Z—Z—Z . . . . A non-limiting,exemplary alternating random configuration may have the non-limitingform: X—Y—X—Z—Y—X—Y—Z—Y—X—Z . . . , and an exemplary regular alternatingconfiguration may have the non-limiting form: X—Y—Z—X—Y—Z—X—Y—Z . . . .An exemplary regular block configuration may have the followingnon-limiting configuration: . . . X—X—X—Y—Y—Y—Z—Z—Z—X—X—X . . . , whilean exemplary random block configuration may have the non-limitingconfiguration: . . . X—X—X—Z—Z—X—X—Y—Y—Y—Y—Z—Z—Z—X—X—Z—Z—Z . . . . In agradient polymer, the content of one or more monomeric units increasesor decreases in a gradient manner from the a end of the polymer to the ωend. In none of the preceding generic examples is the particularjuxtaposition of individual constitutional units or blocks or the numberof constitutional units in a block or the number of blocks meant norshould they be construed as in any manner bearing on or limiting theactual structure of block copolymers forming a micelle described herein.As used herein, the brackets enclosing the constitutional units are notmeant and are not to be construed to mean that the constitutional unitsthemselves form blocks. That is, the constitutional units within thesquare brackets may combine in any manner with the other constitutionalunits within the block, i.e., purely random, alternating random, regularalternating, regular block or random block configurations. The blockcopolymers described herein are, optionally, alternate, gradient orrandom block copolymers. In some embodiments, the block copolymers aredendrimer, star or graft copolymers.

Branched: unless otherwise indicated, “branched” refers to a polymerstructure in which a polymer chain divides into two or more polymerchains.

Brushes/Polymer Brushes: unless otherwise indicated, “brushes” or“polymer brushes” are used herein synonymously and refer to polymerchains that are bound to a surface generally through a single point ofattachment using graft-from techniques. The polymers can be end-grafted(attached via a terminal group) or attached via a side chain or aposition in the polymer chain other than a terminal position. Thepolymers can be linear or branched. For example, the polymer chainsdescribed herein can contain a plurality of side chains that containzwitterionic groups. The side chains can consist of a single non-foulingmoiety or monomer and/or a non-fouling oligomer (e.g., 2-10 monomericresidues) or polymer (e.g., >10 monomeric residues).

Carboxyammonium: unless otherwise indicated, a “carboxyammonium” moietyis a zwitterionic moiety comprising carboxylate and ammoniumfunctionality and includes, for example, carboxyammonium monomers,carboxyammonium oligomers, carboxyammonium polymers, carboxyammoniumrepeat units, and other carboxyammonium-containing materials.Carboxybetaine monomers, oligomers, polymers, repeat units and othercarboxybetaine materials are exemplary carboxyammonium moieties.

Cationic Monomer, Cationic Monomeric Unit or Cationic Repeat Unit:unless otherwise indicated, a “cationic monomer,” “cationic monomericunit” or “cationic repeat unit” is a monomer or a monomeric or repeatunit (the terms “monomeric unit” and “repeat unit” being usedinterchangeably) bearing a cation or other cationic species, e.g., amoiety capable of having a positive charge upon addition of anelectrophile (e.g., a proton (H+) or an alkyl cation, for example in apH dependent manner) or removal of a protecting group or a nucleophile).

Cationic species or Cationic Moiety: unless otherwise indicated, a“Cationic species” or a “Cationic Moiety” is a group, residue ormolecule that is present in a positively charged or non-charged state,but in the non charged state is capable of becoming positively charged,e.g., upon addition of an electrophile (e.g., a proton (H+), for examplein a pH dependent manner) or removal of a protecting group or anucleophile. In certain instances, the group, residue or molecule ispermanently charged, e.g., comprises a quaternary nitrogen atom.

Clarity: unless otherwise indicated, “clarity” refers to the ability oflight to pass through a material as measured by either a UV-visinstrumental technique and/or by visual inspection using a magnifiedoptical comparator tool by a trained operator. Either opacity of thebulk material, which prevents the transmission of light, or surfaceirregularities, which scatter light, may contribute to the overallclarity of a material. For example, using a magnified optical comparatortool, materials may be assigned a clarity score 1-5 as follows: 1=>90%(of surface area inspected) opaque; 2=>50% (of surface area inspected)opaque; 3=>90% (of surface area inspected) transparent, some surfaceirregularities; 4=>99% (of surface area inspected) transparent, fewsurface irregularities observed; 5=100% transparent, no surfaceirregularities observed.

Coating: unless otherwise indicated, “coating” refers to any temporary,semi-permanent or permanent layer, or layers, treating or covering asurface. The coating may be a chemical modification of the underlyingsubstrate or may involve the addition of new materials to the surface ofthe substrate. It includes any increase in thickness to the substrate orchange in surface chemical composition of the substrate.

Contact Angle: unless otherwise indicated, the Contact Angle is aquantitative measure of the wetting of a solid by a liquid. It isdefined geometrically as the angle formed by a liquid at the three phaseboundary where a liquid, gas and solid intersect. If the three phase(liquid/solid/vapor) boundary is in motion, the angles produced arecalled Dynamic Contact Angles and are referred to as ‘advancing’ and‘receding’ angles. Dynamic contact angles may be assayed at variousrates of speed. Advancing angles are measured when the liquid phase isexpanding. Receding angles are measured when the liquid phase iscontracting. For an underwater measurement using an air bubble, theadvancing angle occurs when the air bubble is contracting and thereceding angle is measured when the air bubble is expanding. Unlessotherwise indicated, “Advancing Contact Angle,” as used herein, willrefer to the initial angle measured after contracting an air bubbleunderwater (or appropriate buffer or simulated tear solution) that is incontact with the surface being examined at 1 ul/s to the point that thebase length of the air bubble is no longer decreasing, but the airbubble begins to deform in shape. Unless otherwise indicated, “RecedingContact Angle, as used herein, will refer to the initial angle measuredwhen an underwater air bubble that has been equilibrated for 3 secondswith the surface being examined is enlarged at 1 ul/s and the baselength is observed to increase. The base length will change withoutsubstantially changing the air/solid/liquid interfacial angle as the airbubble is enlarged.

Contact Lens: unless otherwise indicated, a “contact lens” or “lens”refers to a structure that can be placed on or within a wearer's eye. Acontact lens can correct, improve, or alter a user's eyesight, but thatneed not be the case. For example, the contact lens may additionally oralternatively provide optical correction, wound care, drug delivery,diagnostic functionality, cosmetic alterations or enhancement, orcombinations thereof. A lens or contact lens can be of any appropriatematerial known in the art or later developed, and can be a soft lens(e.g., soft, hydrogel lens, soft, non-hydrogel lens and the like), ahard lens (e.g., hard, gas permeable lens materials and the like), ahybrid lens, intraocular lenses, overlay lenses, ocular inserts, opticalinserts, and the like. As is understood by one skilled in the art, alens is considered to be “soft” if it can be folded back upon itselfwithout breaking. Any material known to produce a biomedical deviceincluding an ophthalmic device can be used herein. A “silicone hydrogelcontact lens” refers to a contact lens comprising a silicone hydrogelmaterial (including silicones, silicone derivatives such asfluorosilicones and their copolymers).

Copolymer: unless otherwise indicated, “copolymer” refers to a polymerderived from two, three or more monomeric species and includesalternating copolymers, periodic copolymers, random copolymers,statistical copolymers and block copolymers.

Degradation Products: unless otherwise indicated, “degradation products”are atoms, radicals, cations, anions, or molecules other than waterformed as the result of hydrolytic, oxidative, enzymatic, or otherchemical processes.

Dry Thickness: unless otherwise indicated, “Dry Thickness,” as usedherein in connection with a polymer layer, shall mean the thickness ofthe polymer layer using a scanning electron microscope (SEM). To measuredry thickness, the sample is dehydrated overnight, then freeze fracturedfor imaging by being submerged in liquid nitrogen then cracked with anultra microtome blade. The freeze fracturing should break the article ata plane approximately orthogonal to the polymer modified surface inorder to measure the thickness of the polymer layer normal to thesubstrate. The samples are sputter coated in gold for 90 seconds using asputter coater and then imaged under high vacuum at 5 kV using an SE2detector under a Field Emission Scanning Electron Microscope (FESEM).Exemplary microtome blades include the Leica Ultracut UCTUltramicrotome, exemplary sputter coaters include the Cressington 208HR,exemplary SEMS include the Supra55VP FESEM, Zeiss. Dry thickness may beapproximated by analyzing intensity of chemical signals in the graftedpolymer, for instance, through the use of ATR-FTIR.

Fibrinogen Adsorption Assay: unless otherwise indicated, a “FibrinogenAdsorption Assay” is an assay used to assess the capacity of a surfacefor fibrinogen. In the assay, test samples are placed in a suitablesized container, which may be a 96-well manifold, microcentrifuge tube,or other container. The volumes in the following are appropriate for adeep 96-well plate, but may be scaled to properly cover a device beingtested. The samples are sterilized in an autoclave and the test groupsrun with an n per run of 3-4. The sample container is blocked with 20mg/mL Bovine Serum Albumin (BSA) in 1×PBS for 1 hour at 4° C., followedby three rinses with 1×PBS before samples are added. The sample isexposed to a solution containing 70 μg/mL unlabeled human fibrinogen,1.4 μg/mL I-125 radiolabeled human fibrinogen, 35-55 μg/mL BSA in water,optionally tri-sodium citrate, and optionally sodium chloride. The BSAis a common agent co-lyophilized with the radiolabeled fibrinogen.Optionally, the BSA and radiolabeled fibrinogen may have been dissolvedfrom a lyophilized form that contains tri-sodium citrate and sodiumchloride. The samples are incubated for one hour at 37° C. on an orbitalshaker at 150 RPM. The test solution is then removed and four 1-minuterinses with a 10 mM NaI and one 1-minute rinse with 1×PBS is performed.The samples are loaded into a gamma counter. The counter measures theradioactivity in I-125 counts per minute for each sample and this datais used to calculate the absolute fibrinogen adsorption or a percentreduction of the non-fouling polymer layer samples versus a referencesubstrate, that is, the same or an otherwise functionally equivalentsubstrate lacking the non-fouling polymer layer. The percent reductionis equal to: (1−non-fouling sample CPM/Average CPM of the referencesubstrate)*100%.

Global Average Dry Thickness: unless otherwise indicated, “GlobalAverage Dry Thickness,” as used herein in connection with a polymerlayer, shall mean the mean calculated by averaging the Local Average DryThickness of at least 3, and preferably at least 5, representativelocations spaced approximately evenly across the portion of the articlecarrying the polymer layer. It is preferred to measure the thickness atrepresentative points across the longest dimension of the portion of thearticle that is covered with the polymer layer. The standard deviationof the Global Average Dry Thickness is found by calculating the standarddeviation of the Local Average Dry Thickness across at least 5, andpreferably at least 10, representative locations spaced approximatelyevenly across the portion of the article carrying the polymer layer.

Global Average Humidified Thickness: unless otherwise indicated, “GlobalAverage Humidified Thickness,” as used herein in connection with apolymer layer, shall mean the mean calculated by averaging the LocalAverage Humidified Thickness of at least 3, and preferably at least 5,representative locations spaced approximately evenly across the portionof the article carrying the polymer layer. It is preferred to measurethe thickness at representative points across the longest dimension ofthe portion of the article that is covered with the polymer layer. Thestandard deviation of the Global Average Humidified Thickness is foundby calculating the standard deviation of the Local Average HumidifiedThickness across at least 5, and preferably at least 10, representativelocations spaced approximately evenly across the portion of the articlecarrying the polymer layer.

Global Average R_(rms) Surface Roughness: unless otherwise indicated,“Global Average R_(rms) Surface Roughness,” as used herein in connectionwith a polymer layer, shall mean the mean calculated by averaging theR_(rms) surface roughness of at least 5, and preferably at least 10,representative locations spaced approximately evenly across the portionof the article carrying the polymer layer. It is preferred to measurethe thickness at representative points across the longest dimension ofthe portion of the article that is covered with the polymer layer. Thestandard deviation of the Global Average R_(rms) Surface Roughness isfound by calculating the standard deviation of the Local Average R_(rms)Surface Roughness across at least 5, and preferably at least 10,representative locations spaced approximately evenly across the portionof the article carrying the polymer layer.

Graft: unless otherwise indicated, the term “graft,” as used herein inconnection with a polymer, means the modification of the surface of amaterial with a polymer by a “graft-from”, “graft-through”, or a“graft-to” approach, or a combination thereof to form a grafted polymer.

Graft-from method: unless otherwise indicated, the term “graft-from,” asused herein in connection with a method for the modification of amaterial with a polymer, shall mean the in situ polymerization andgrowth of a polymer at the surface of, or within a material.

Graft-from polymer: unless otherwise indicated, the term “graft-frompolymer,” as used herein, shall mean a polymer formed by a graft-frommethod.

Graft-through method: unless otherwise indicated, the term“graft-through,” as used herein in connection with a method for themodification of a material with a polymer, shall mean the in situpolymerization of monomers in the neighborhood of the material that maypolymerize through functional groups presented from the materialsurface. For example, the material may have vinyl groups presented fromthe surface through which polymerization occurs.

Graft-through polymer: unless otherwise indicated, the term“graft-through polymer,” as used herein, shall mean a polymer formed bya graft-through method.

Graft-to method: unless otherwise indicated, the term “graft-to,” asused herein in connection with a method for the modification of amaterial with a polymer shall mean the modification of the surface of amaterial with a resynthesized polymer

Graft-to polymer: unless otherwise indicated, the term “graft-topolymer,” as used herein, shall mean a grafted polymer formed by agraft-to method.

Heteroaryl: unless otherwise indicated, the term “heteroaryl” means anaryl group wherein at least one of the ring members is a heteroatom, andpreferably 5 or 6 atoms in each ring. The heteroaromatic grouppreferably has 1 or 2 oxygen atoms, 1 or 2 sulfur atoms, and/or 1 to 4nitrogen atoms in the ring, and may be bonded to the remainder of themolecule through a carbon or heteroatom. Exemplary heteroaromaticsinclude furyl, thienyl, pyridyl, oxazolyl, pyrrolyl, indolyl,quinolinyl, or isoquinolinyl and the like. Exemplary substituentsinclude one or more of the following groups: hydrocarbyl, substitutedhydrocarbyl, keto (i.e., ═O), hydroxy, protected hydroxy, acyl, acyloxy,alkoxy, alkenoxy, alkynoxy, aryloxy, halogen, amido, amino, nitro,cyano, thiol, ketals, acetals, esters and ethers.

Heteroatom: unless otherwise indicated, the term “heteroatom” means anatom other than hydrogen or carbon, such as a chlorine, iodine, bromine,oxygen, sulfur, nitrogen, phosphorus, boron, arsenic, selenium orsilicon atom.

Heterocyclo: unless otherwise indicated, the terms “heterocyclo” and“heterocyclic” as used herein alone or as part of another group denoteoptionally substituted, fully saturated or unsaturated, monocyclic orbicyclic, aromatic or nonaromatic groups having at least one heteroatomin at least one ring, and preferably 5 or 6 atoms in each ring. Theheterocyclo group preferably has 1 or 2 oxygen atoms, 1 or 2 sulfuratoms, and/or 1 to 4 nitrogen atoms in the ring, and may be bonded tothe remainder of the molecule through a carbon or heteroatom. Exemplaryheterocyclo include heteroaromatics such as furyl, thienyl, pyridyl,oxazolyl, pyrrolyl, indolyl, quinolinyl, or isoquinolinyl and the like.Exemplary substituents include one or more of the following groups:hydrocarbyl, substituted hydrocarbyl, keto, hydroxy, protected hydroxy,acyl, acyloxy, alkoxy, alkenoxy, alkynoxy, aryloxy, halogen, amido,amino, nitro, cyano, thiol, ketals, acetals, esters and ethers.

Heterohydrocarbyl: unless otherwise indicated, the term“heterohydrocarbyl” means a hydrocarbyl group wherein at least one ofthe chain carbon atoms is replaced with a heteroatom.

Humidified Thickness: unless otherwise indicated, “humidifiedthickness,” as used herein in connection with a polymer layer, shallmean the thickness of the polymer layer using an environmental scanningelectron microscope (ESEM and approximately 26% relative humidity). Tomeasure humidified thickness, the sample is freeze fractured for imagingby being submerged in liquid nitrogen then cracked with an ultramicrotome blade. The freeze fracturing should break the article at aplane orthogonal to the polymer modified surface in order to measure thethickness of the polymer layer normal to the substrate. Afterfracturing, the samples are soaked in water for at least one hour andthen submerged in liquid nitrogen and fixed to a cold stage at −8° C. to−12° C. The samples are then imaged using a VPSE detector at the highestresolvable humidity (approximately 26% or 81 Pa) under a ScanningElectron Microscope (SEM) with an Environmental Scanning ElectronMicroscope (E-SEM). Exemplary microtome blades include the LeicaUltracut UCT Ultramicrotome, exemplary SEMS include the Supra55VP FESEM,Zeiss, and exemplary E-SEMS include the Zeiss EVO 55.

Hydrocarbon or Hydrocarbyl: unless otherwise indicated, the terms“hydrocarbon” and “hydrocarbyl” as used herein describe organiccompounds or radicals consisting exclusively of the elements carbon andhydrogen. These moieties include alkyl, alkenyl, alkynyl, and arylmoieties. These moieties also include alkyl, alkenyl, alkynyl, and arylmoieties substituted with other aliphatic or cyclic hydrocarbon groups,such as alkaryl, alkenaryl and alkynaryl. Unless otherwise indicated,these moieties preferably comprise 1 to 20 carbon atoms

Hydrophilic: unless otherwise indicated, “hydrophilic” refers tosolvents, molecules, compounds, polymers, mixtures, materials, orfunctional groups which have an affinity for water. Such materialstypically include one or more hydrophilic functional groups, such ashydroxyl, zwitterionic, carboxy, amino, amide, phosphate, sulfonyl,hydrogen bond forming, and/or ether groups.

Hydrophilic polymer: unless otherwise indicated, “hydrophilic polymer”refers to a polymer surface that has an affinity for water. One methodof determining a polymer surface's affinity to water is measuring thecontact angle. For the purposes of this application, a surface will bedefined as hydrophilic if it has an advancing contact angle less than 50degrees. A super hydrophilic polymer will refer to a polymer surfacewith an advancing contact angle less than 30 degrees.

Hydrophobic: unless otherwise indicated, “hydrophobic” refers tosolvents, molecules, compounds, polymers, mixtures, materials, orfunctional groups that are repelled by water. Such materials typicallycontain non-polar functional groups.

Hydrophobic polymer: unless otherwise indicated, “hydrophobic polymer”refers to a polymer surface that is repelled by water. One method ofdetermining if a polymer surface is hydrophobic is by measuring acontact angle. For the purposes of this application, a polymer surfacewill be defined as hydrophobic if an advancing contact angle is greaterthan 50 degrees. A super hydrophobic polymer will refer to a polymersurface with an advancing contact angle greater than 80 degrees.

Immobilization/Immobilized: unless otherwise indicated, “immobilization”or “immobilized” refers to a material or bioactive agent that iscovalently or non-covalently attached directly or indirectly to asubstrate. “Co-immobilization” refers to immobilization of two or moreagents.

Initiator: unless otherwise indicated, “initiator” refers to a substanceor a combination of substances that can produce a radical or otherspecies under relatively mild conditions and promote polymerizationreactions. For example, redox pairs as described elsewhere herein may bean initiator.

Local Average Dry Thickness: unless otherwise indicated, “Local AverageDry Thickness” is the mean Dry Thickness calculated by averaging DryThickness measurements of at least 3, and preferably at least 5,representative locations spaced approximately evenly across a crosssection of the article that spans approximately 80-120 micrometers. Thestandard deviation of the Local Average Dry Thickness is determined bycalculating the standard deviation of the Dry Thickness across at least5, and more preferably at least 10, representative locations spacedapproximately evenly across a cross section of article that spansapproximately 80-120 micrometers.

Local Average Humidified Thickness: unless otherwise indicated, “LocalAverage Humidified Thickness” is the mean Humidified Thicknesscalculated by averaging Humidified Thickness measurements of at least 3,and preferably at least 5, representative locations spaced approximatelyevenly across a cross section of the article that spans approximately80-120 micrometers. The standard deviation of the Local AverageHumidified Thickness may be determined by calculating the standarddeviation of the Humidified Thickness across of at least 5, andpreferably at least 10, representative locations spaced approximatelyevenly across a cross section of article that spans approximately 80-120micrometers.

Lubricity: unless otherwise indicated, “lubricity” refers to thecapacity of a surface modification for reducing friction. For example, ahighly lubricious surface would be one that has a coefficient offriction of about 0.01 to about 0.03, whereas a poorly lubricous surfacewould be one that has a coefficient of friction of about 0.35 to about0.6. One method of performing friction measurements utilizes amicrotribometer (Basalt® Must, Tetra®, Germany) according to the methodof Roba, et al. (Friction Measurements on contact Lenses in theirOperating Environment, Tribol Lett (2011) 44:387-397). Cantilevers(Tetra®, Germany) with different ranges of spring stiffness (N/m) areused: kn=23, kt=23, +/−10% and kn=15, kt==15, +/−10% (kn is the normalforce spring constant and kt is the tangential force spring constant).The contact lens is placed inside a Teflon® chamber on top of asand-blasted rounded plastic holder (cyclo olefin polymer, Johnson &Johnson Vision Care inc., USA), matching the internal radius ofcurvature of the lens, and is held in position by a cast silicone-rubbercover (polyvinylsiloxane, provil Novo, Germany) and plastic ring(poly(methyl methacrylate), PMMA). Silicone cover and PMMA ring arescrewed to the Teflon® chamber by two screws placed at 180° to oneanother. The anterior surface of the lens faces upward. The countersurface consists of a functionalized 5-mm diameter glass disk (coverglass, Thermo Scientific, Germany). A 6 mm long glass rod is glued ontothe tip of the tribometer cantilever. The functionalized glass disk isglued to the glass rod with cyanoacrylate and mounted in the tribometer.A contact lens is brought into contact with the glass disk. Contact areaand pressure between the flat glass disk and the soft contact lens aremeasured with a tear-mimicking solution as lubricant and mucin-coatedsilanized glass disk at 0, 50 and 100 cycles. Unmodified lenses measureaverage coefficient of friction about 0.4 whereas modified lensesmeasure about 0.02.

Macromer: unless otherwise indicated, “macromer” refers to a medium andhigh molecular weight compound or polymer that contains at least onecrosslinkable group and can be polymerized and/or crosslinked to form apolymer. Medium and high molecular weight typically means averagemolecular weights greater than 700 Daltons.

Monomer: unless otherwise indicated, “monomer” means a low molecularweight compound that can be polymerized. Low molecular weight typicallymeans average molecular weights less than 700 Daltons.

Non-Degradable: unless otherwise indicated, “non-degradable” refers tomaterial compositions that do not react significantly within abiological environment either hydrolytically, reductively, enzymaticallyor oxidatively to cleave into smaller or simpler components.

Non-Fouling Composition/Non-Fouling Material/Non-FoulingPolymer/Non-Fouling Polymer Layer: unless otherwise indicated, a“non-fouling composition” or “non-fouling material” or “non-foulingpolymer” or “Non-fouling polymer layer” as used interchangeably herein,is a composition that provides or increases the protein resistance of asurface of an article to which the composition is attached. For example,when attached to a substrate such a composition may resist the adhesionof proteins, including blood proteins, plasma, cells, tissue and/ormicrobes to the substrate relative to the amount of adhesion to areference substrate, that is, the same or an otherwise functionallyequivalent substrate lacking the composition. Preferably, a substratesurface will be substantially non-fouling in the presence of humanblood. Preferably the amount of adhesion will be decreased 20%, 30%,40%, 50%, 60%, 70%, 80%, or more, for example, 85%, 90%, 95%, 99%,99.5%, 99.9%, or more, relative to the reference substrate. Oneparticularly preferred measure of the non-fouling character or proteinresistance of a surface is the amount of fibrinogen adsorbed in aFibrinogen Adsorption Assay as described herein. Preferably, the amountof adsorbed fibrinogen using the Fibrinogen Adsorption Assay describedherein is <125 ng/cm², <90 ng/cm², <70 ng/cm², <50 ng/cm², <30 ng/cm²,<20 ng/cm², <15 ng/cm², <12 ng/cm², <10 ng/cm², <8 ng/cm², <6 ng/cm², <4ng/cm², <2 ng/cm², <1 ng/cm², <0.5 ng/cm², or <0.25 ng/cm².

Ophthalmic device: unless otherwise indicated, an ophthalmic devicerefers to a contact lens (hard or soft), an intraocular lens, a cornealonlay, or other ophthalmic devices (e.g., stents, glaucoma shunt, or thelike) used on or about the eye or ocular vicinity.

Oxygen Permeability: unless otherwise indicated, the “oxygenpermeability” will refer to the rate at which oxygen will pass through amaterial. Intrinsic “oxygen permeability”, Dk, of a lens material doesnot depend on lens thickness. Oxygen permeability is conventionallyexpressed in units of barrers, where “barrer” is defined as:[(cm³oxygen)(mm)/(cm²)(sec)(mm²Hg)]×10⁻¹⁰. These are the units commonlyused in the art. Thus, in the interest of consistency, the unit “barrer”will have the meanings as defined above. For example, a lens having a Dkof 90 barrers (“oxygen permeability barrers”) and a thickness of 90microns (0.090 mm) would have a Dk/t of 100 barrers/mm:[(90×10⁻¹⁰/0.09)=100×10⁻⁹]. In accordance with the disclosure, a highoxygen permeability in reference to a material or a contact lenscharacterized by apparent oxygen permeability of at least 40 barrers orlarger measured with a sample (film or lens) of 100 microns in thicknessaccording to a coulometric method. One particular coulometric method ofdetermining oxygen permeability is by ASTM F1927-07-Standard Test Methodfor Determination of Oxygen Gas Transmission Rate, Permeability andPermeance at Controlled Relative Humidity Through Barrier MaterialsUsing a Coulometric Detector.

Oxygen transmissibility: unless otherwise indicated, the “oxygentransmissibility” of a contact lens, as used herein, is the rate atwhich oxygen will pass through a specific ophthalmic lens. Oxygentransmissibility, Dk/t, is conventionally expressed in units ofbarrers/mm, where t is the average thickness of the material [in unitsof mm] over the area being measured and “barrer/mm” is defined as:[(cm³oxygen)/(cm²)(sec)(mm²Hg)]×10⁻⁹.

Penetration Depth: unless otherwise indicated, the “penetration depth”will refer to the distance the surface modification polymer extendsbelow the surface of the lens in a direction normal to the surface ofthe lens. The distance may be measured given a distinct chemical signalor selective staining for the surface modification polymer. The distancemay be normalized to the body of the contact lens. The boundary for theregion containing the surface modification may be defined as thedistance that the polymer modification penetrates into the substrate asdetected visually after staining with a dye that binds to themodification (e.g. eosin for sulfobetaine or osmium tetroxide forcarboxybetaine), or by EDS, the region in which the atomic % signal isat least 2×baseline. See FIGS. 1-4. Representative chemical signalassessments include: SEM-EDS, FTIR-microscope, and XPS. The penetrationdepth profile can be determined, e.g., using eosin, acid molybdatereagent, orange B, EDS, SEM staining, osmium tetroxide, and hydrophobicstaining. For example, a modified contact lens can be dehydrated underair overnight and then cut into a piece of 5×5 mm square. The sample isthen observed under an SEM. The elemental composition of thecross-section surface, especially sulfur and silicon, is mapped usingEDS. Alternatively, the sample can be embedded in paraffin wax prior tostaining and analysis. Paraffin wax is melted in a glass container in a60° C. oven (30 minutes to 1 hour). The sample is placed on the bottomof a metal mold and the melted wax poured into the mold. After cooling,the embedded lens in paraffin wax is microtomed to 10 μm-thick sections.The microtomed sections are then put on a glass slide heated to 60° C.After the paraffin is melted and cooled to room temperature, theparaffin wax is dissolved with Neo-Clear xylene substitute or othersolvents. Then the sample is stained in 2% Eosin in H₂O for two minutesand rinsed with water until no color changes are observed. The samplescan be observed by optical or laser microscopy. An alternative methodcan be performed by staining a piece of 5 mm square from a contact lensin 2% Eosin in H₂O for two minutes prior to embedding in paraffin wax.The samples are rinsed with water until no color changes are observed.The sample is then embedded in paraffin wax and microtomed to 10μm-thick sections from the embedded sample. The sections are melted on aglass slide, cooled, and the paraffin wax is removed by Neo-Clear xylenesubstitute or other solvents. The samples can be observed by optical orlaser microscopy. Another alternative method is to break the stainedsamples in liquid nitrogen and the fresh cross-section can be observedunder an optical or laser microscope.

Photoinitiator: unless otherwise indicated, a “photoinitiator” refers toa chemical that initiates radical crosslinking/polymerizing reaction bythe use of light (visible, ultraviolet or infrared). Suitablephotoinitiators include, without limitation, benzoin methyl ether,diethoxyacetophenone, benzoylphosphine oxide, 1-hydroxycyclohexyl phenylketone, Darocure® types, and Irgacure® types, preferably Darocure® 1173,and Irgacure® 2959.

Polymer: unless otherwise indicated, “polymer” includes natural andsynthetic, homopolymers and copolymers comprising multiple repeat unitsand, unless otherwise indicated, may be linear, branched, or dendritic.Examples of copolymers include, but are not limited to, randomcopolymers and block copolymers, smart polymers, temperature responsive(e.g., NIPAM), and pH responsive (e.g., pyridyl based) polymers.

Quaternary Nitrogen: unless otherwise indicated, “quaternary nitrogen,”as used herein, refers to a nitrogen atom that is a member of aquaternary ammonium cation.

R_(rms) Surface Roughness: unless otherwise indicated, “R_(rms) SurfaceRoughness” refers to root mean squared roughness of a surface, whichmeasures the vertical deviations of a real surface from its ideal form.The roughness refers to surface micro-roughness which may be differentthan measurements of large scale surface variations. Preferably, thismay be measured using atomic force microscopy (MFP-3D, Asylum) across afield of approximately 1-30 μm by 1-30 μm, preferably 20 μm by 20 μm.The sample can be measured both in hydrated or dehydrated condition.Standard silicon cantilever (Olympus AC160TS, spring constant 42 N/m) isemployed for the measurement with an AC/Tapping mode. The R_(rms)surface roughness is calculated by the software (IGOR Pro) attached withthe AFM machine. Alternatively the roughness can be measured using astylus profilometer. For example, the sample surface roughness can bemeasured by a Tencor P-16+ profilometer with a 60 degree, 2 μm diamondtip stylus. Preferably, an 800 μm scan length is chosen with 20μm/second scan rate, 50 Hz scan frequency, and 2 μg loading force. Atleast three different sites are measured for the same sample, and thesurface roughness is averaged from at least three samples.Alternatively, the R_(rms) surface roughness can be measured preferablyby non-contact methods, including using optical profilometers. Forexample, the sample surface roughness is measured by a opticalprofilometer (Zeta Z20 or Olympus Lext OLS4000). Preferably a 3-D imageis taken by the optical profilometer under a 50× objective lens, and thesample's surface roughness is then measured along at least threedifferent lines cross the image. At least three different spots aremeasured and the surface roughness is averaged from at least threesamples. In a preferred example an Olympus LEXT OLS4000 3D LaserMeasuring Microscope is employed for roughness measurements and 3Dimaging. A LEXT microscope utilizes low wavelength optical technologywith a 408 nm laser in combination with confocal scanning can be usedfor the measurement. Samples to be measured are mounted on a glass slideby double-sided tape. Digital 3-D images are taken with the Olympus LEXTOLS4000 laser confocal microscope (“LEXT”) under an Olympus MPLAPON 50×objective lens. The digital images taken in this way have a 256×256 μmfield area. The Z-direction repeatability for this LEXT machine has beencertified by Olympus to be less than 0.012 μm. To measure the roughness,at least three images have been taken from each sample and the R_(rms)roughness is calculated by using a 9 μm cut-off length.

Silicate: unless otherwise indicated, “silicate” or “silicates” refersto a compound containing a silicon-bearing anion.

Silicon: unless otherwise indicated, “silicon” or “Si” refers to thechemical element with the symbol Si and atomic number 14.

Silicone: unless otherwise indicated, “silicone” or “silicones” arepolymers that include silicon together with carbon, hydrogen, oxygen,and, optionally, other chemical elements (e.g., nitrogen, chlorine, andphosphorus).

Silicone hydrogel: unless otherwise indicated, “silicone hydrogel refersto a silicone-containing hydrogel obtained by copolymerization of apolymerizable composition comprising at least one silicone-containingmonomer or at least one silicone-containing macromer or at least onecrosslinkable silicone-containing prepolymer. Silicone hydrogels mayinclude silicones, silicone derivatives such as fluorosilicones andtheir copolymers.

Siloxane: unless otherwise indicated, “siloxane” or “siloxanes” refersto any chemical compound composed of units having the formula R₂SiO,where R is hydrogen or hydrocarbyl.

Solvent Extractable Polymerization Initiator: unless otherwiseindicated, “Solvent Extractable Polymerization Initiator” refers to anycompound capable of starting radical polymerization that has beenincorporated within the article, wherein either the initiator or itsdegradation products may be extracted from the article using a suitablesolvent. In general, extractions can use nonpolar or polar solvents. Forexample, extraction solvents such as water, acetone or ethanol; and/orother extraction solvents in which the solubility of the initiatorand/or its degradation products is at least 1 mg/L. The extractionshould be carried out for a sufficient time such that the change inconcentration of the extract is not increasing more than 5% per hour.Alternatively, extraction until the amount of extracted material in asubsequent extraction is less than 10% of that detected in the initialextraction, or until there is no analytically significant increase inthe cumulative extracted material levels detected. Extraction conditionsinclude: 37° C. for 72 h; 50° C. for 72 h; 70° C. for 24 h; 121° C. for1 h. Extraction ratio includes 6 cm²/mL surface area/volume and/or 0.2 gsample/mL. In some instances, complete dissolution of the substrate maybe appropriate. Materials shall be cut into small pieces beforeextraction to enhance submersion in the extract media, for example, forpolymeric substrates approximately 10 mm×50 mm or 5 mm×25 mm areappropriate. The instrumentation used includes high-performance liquidchromatography-photo-diode array detection-mass spectrometry(HPLC-PDA-MS) for organics analysis; gas chromatography-massspectrometry (GC-MS) for organics analysis; inductively coupledplasma-optical emission spectroscopy or mass spectrometry (ICP-OES orICP-MS) for metals analysis; and sometimes ion chromatography (IC) forinorganics and ion analysis. Sometimes more advanced MS detectors suchas time-of-flight (TOF) are used to obtain accurate mass information.Hexane and alcohol extractions are analyzed by GC-MS. Water and alcoholextractions are analyzed by HPLC. The initiator or its degradationproducts may be quantified and/or detected in the substrate or graftedpolymer by the previously described methods. These include FTIR-ATR,electron spectroscopy for chemical analysis (ESCA, also called X-rayphotoelectron spectroscopy, XPS), Secondary Ion Mass Spectrometry(SIMS), and surface-enhanced Raman spectroscopy (SERS). For example,peroxide may be detected spectrophotometrically using any of thefollowing three methods: the iodide method (oxidation of sodium iodideby peroxides in the presence of ferric chloride), the DPPH method(treatment with 1,1-diphenyl-2-picrylhydrazyl, a radical scavenger, todecompose the peroxides), or the peroxidase method (reduction withglutathione, catalyzed by glutathione peroxidase, followed by measuringthe coupled oxidation of NADPH in the presence of glutathionereductase). See, for example, Fujimoto et al., Journal of PolymerScience Part A: Polymer Chemistry, Vol. 31, 1035-1043 (1993).

Stable: unless otherwise indicated, “stable,” as used herein inreference to a material, means that the material retains functionalityover extended periods of time. In one embodiment, the referencedmaterial retains at least 90% of a referenced activity (or property) forat least 30 days at 37° C. in at least one of phosphate buffered salinecontaining protein, media, or serum, or in vivo. In one embodiment, thereference material retains at least 80% of a referenced activity (orproperty) for at least 90 days at 37° C. in at least one of phosphatebuffered saline containing protein, media, or serum, or in vivo. In oneembodiment, the referenced material retains at least 90% of thereferenced activity (or property) for at least 30 days at 37° C. and atleast 80% of the referenced activity (or property) for at least 90 daysat 37° C. The referenced activity or property may include surfacecontact angle, non-fouling, anti-thrombogenic, and/or antimicrobialactivity.

Static Contact Angle: Unless otherwise indicated, “Static Contact Angle”is the angle at which a water/vapor interface meets a solid substratesurface at or near equilibrium conditions. A drop of purified water(e.g., 1 μL) is deposited on the test surface, the shape of the“sessile” droplet is photographed by a microscope with a CCD camerausing a video contact angle system (e.g., VCA 2000, AST Inc.), and thecontact angle is then determined (using, for example, a VCA Optima XE).The size of the water droplet used to determine the contact angle mayvary depending upon the substrate type and composition. For contactlenses an underwater captive bubble technique is often used instead of asessile drop. The contact lens is submerged under water, a curved needleis used to deliver an air bubble to the surface of the contact lens, andthe angle of the air/liquid/solid interface is measured. In some cases,if the surface is very hydrophilic, upon release from the needle the airbubble does not interact with the contact lens and floats away.

Substantially Non-Cytotoxic: unless otherwise indicated, “substantiallynon-cytotoxic” refers to a composition that does not substantiallychange the metabolism, proliferation, or viability of mammalian cellsthat contact the surface of the composition. These may be quantified bythe International Standard ISO 10993-5 which defines three main tests toassess the cytotoxicity of materials including the extract test, thedirect contact test and the indirect contact test.

Substantially Non-Toxic: unless otherwise indicated, “substantiallynon-toxic” means a surface that is substantially hemocompatible andsubstantially non-cytotoxic.

Substituted/Optionally Substituted: unless otherwise indicated, the term“substituted” and “optionally substituted” means that the referencedgroup is or may be substituted with one or more additional suitablegroup(s), which may be individually and independently selected, forexample, from acetals, acyl, acyloxy, alkenoxy, alkoxy, alkylthio,alkynoxy, amido, amino, aryl, aryloxy, arylthio, azido, carbonyl,carboxamido, carboxyl, cyano, esters, ethers, hydrocarbyl, substitutedhydrocarbyl, heterohydrocarbyl, substituted heterohydroalkyl,cycloalkyl, halogen, heteroalicyclic, heteroaryl, hydroxy, isocyanato,isothiocyanato, ketals, keto, mercapto, nitro, perhaloalkyl, silyl,sulfamoyl, sulfate, sulfhydryl, sulfonamido, sulfonate, sulfonyl,sulfoxido, thiocarbonyl, thiocyanato, thiol, and/or the protectedderivatives thereof. It will be understood that “substitution” or“substituted” includes the implicit proviso that such substitution is inaccordance with permitted valence of the substituted atom and thesubstituent, and that the substitution results in a stable compound,e.g., which does not spontaneously undergo transformation such as byrearrangement, cyclization, elimination, etc.

Substrate: unless otherwise indicated, “substrate” refers to thematerial from which a non-fouling polymer is grafted.

Sulfoammonium: unless otherwise indicated, a “sulfoammonium” moiety is azwitterionic moiety comprising sulfate and ammonium functionality andincludes, for example, sulfoammonium monomers, sulfoammonium oligomers,sulfoammonium polymers, sulfoammonium repeat units, and othersulfoammonium-containing materials. Sulfobetaine monomers, oligomers,polymers, repeat units, and other sulfobetaine materials are exemplarysulfoammonium moieties.

Surviving a digital rubbing test: unless otherwise indicated, “survivinga digital rubbing test” in reference to surface modification on acontact lens as described herein means that after digitally rubbing thelens with a nitrile-gloved hand in the presence of a contact lens washsolution or an equivalent, there is no noticeable increase in contactangle. Representative wash solutions include AQuify Multi-PurposeSolution (MPS) (Ciba Vision), Opti-Free Replenish Multi-PurposeDisinfecting Solution (Alcon), Renu Multi-Purpose Solution (Bausch &Lomb), Biotrue Multi-Purpose Solution (Bausch & Lomb), CompleteMulti-Purpose Solution Easy Rub Formula, and Clear Care (Ciba Vision).Preferably, “surviving a digital rubbing test” in reference to surfacemodification on a contact lens as described herein means that afterdigitally rubbing the lens for 20 seconds as described above, theadvancing contact angle does not increase by more than 5%, 10%, 15%,20%, or 25% from the advancing contact angle prior to the test.

Tear-Film Break-Up: unless otherwise indicated, “tear-film break-uptime” refers to the time between blinks that an observed intact film ismaintained on the outside surface of the cornea in the absence of acontact lens, or the outside surface of a contact lens. In general, toobtain tear-film break-up times, patients are asked to hold both eyesopen while the examiner times the interval from the last blink to thefirst break, dry spot, or distortion occurring in the tear pattern.Patients are encouraged to blink if they feel discomfort, to avoidreflex tearing. If a patient blinks during the test sequence before tearfilm break-up, he or she is instructed to rest briefly to allow the tearfilm to stabilize, and the measure is repeated with reinforcement of theinstructions. Three measurements of the tear-film break-up time aretaken, and an average is used in statistical analyses. One particularmethod of measuring tear-film break-up time is described in Nichols etal., Ophthalmology & Visual Science, April 2006, Vol. 47, No. 4, p.1319-1328.

Thermal initiator: unless otherwise indicated, a “thermal initiator”refers to a chemical that initiates radical crosslinking/polymerizingreaction by the use of heat energy. Examples of suitable thermalinitiators include, but are not limited to, 2,2′-azobis(2,4-dimethylpentanenitrile), 2,2′-azobis (2-methylpropanenitrile),2,2′-azobis (2-methylbutanenitrile), peroxides such as benzoyl peroxide,and the like. Preferably, the thermal initiator is2,2′-azobis(isobutyronitrile) (AIBN).

Undercoating Layer: unless otherwise indicated, “undercoating layer”refers to any coating, or combination of coatings, incorporated into asubstrate from which a non-fouling polymer is grafted.

Zwitterion/Zwitterionic Material: unless otherwise indicated,“zwitterion” or “zwitterionic material” refers to a macromolecule,material, or moiety possessing both cationic and anionic groups. In mostcases, these charged groups are balanced, resulting in a material withzero net charge.

Zwitterionic Polymers: unless otherwise indicated, “zwitterionicpolymers” may be homopolymers or copolymers and include bothpolyampholytes (e.g., polymers with the charged groups on differentmonomer units) and polybetaine (polymers with the anionic and cationicgroups on the same monomer unit). Exemplary zwitterionic polymersinclude alternating copolymers, statistical copolymers, randomcopolymers and block copolymers of two, three or more monomers.

DETAILED DESCRIPTION

One aspect of the present invention is directed to a medical device,such as a contact lens, with a surface modification. Where the medicaldevice is a contact lens, for example, the contact lens is preferably asilicon-containing hydrogel (including silicones, silicone derivativessuch as fluorosilicones and their copolymers). The modification createsa structure such that the surface modification polymer is covalentlyintegrated to the surface of the bulk substrate material, e.g., acontact lens. Among other features, the surface modification isnon-leaching and stable. For example, a surface modified contact lens isstable under various sterilization environments, including multipleautoclave cycles. Additionally, or alternatively, the modification isstable under oxidative solutions, contact lens washing solutions, and UVexposure. The modified article is also durable, withstanding mechanicalchallenges such as surviving a digital rubbing test and friction testsfor contact lenses.

Processes described herein for preparing the articles involve theapplication of hydrophilic polymers to the surface of the article (e.g.,contact lenses). In certain embodiments, the monomers are preferablyzwitterionic compounds, including sulfobetaines, carboxybetaines,phosphorylcholines, and their derivatives. Without being bound to anyparticular theory, it is believed that these polymers provide highwettability, lubricity, and deposition resistance that can improve thecomfort of contact lenses during daily and extended wear. The polymersmay also reduce infection by resisting the adherence of microbes.Preferably, the surface modifications described herein do notsubstantially affect these and other mechanical properties of themedical device. With respect to contact lenses, for example, the shapeof the lens is relevant to visual acuity and the edges are designed forcomfort and the surface modifications do not adversely affect theseproperties.

In general, the surface modification may be applied through a wetchemistry method using relatively mild conditions as described herein.The methods described herein preferably utilize only liquid reactions.In preferred embodiments, a minimum number of steps are required, andthe steps are amenable to current contact lens manufacturing processes.In preferred embodiments, five, four, three, two or one reaction step(s)are used. Advantageously, no plasma treatment is required.

In some embodiments, the surface modification polymer layer extends intothe contact lens base material. Without being bound to any theory, thedepth of surface modification on the surface of and into the bulkmaterial may improve attachment of the surface modification polymerchains, which may, in turn, improve the resistance of the modifieddevice to abrasion or chemical stresses. In one embodiment, the surfacemodification polymer extends at least a minimum penetration depth of0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or 45% of the thicknessof the lens below the surface of the lens in a direction normal to thesurface of the lens. Thus, for example, the surface modification polymermay extend a minimum penetration depth of about 0.1% to about 0.5%,about 0.1% to about 2%, about 0.1% to about 10%, or about 0.1% to about30%. By way of another example, the surface modification polymer mayextend a minimum penetration depth of about 0.5% to about 1%, about 0.5%to about 5%, about 0.5% to about 20%, or about 0.5% to about 40%. By wayof another example, the surface modification polymer may extend aminimum penetration depth of about 1% to about 5%, about 1% to about10%, about 1% to about 20%, or about 1% to about 40%. In one embodiment,the polymeric surface modification material in each of the foregoingembodiments and examples recited in this paragraph is a zwitterionicpolymer. In one embodiment, the polymeric surface modification materialin each of the foregoing examples and embodiments recited in thisparagraph is a polymer containing carboxyammonium or sulfoammoniumrepeat units. In one embodiment, the polymeric surface modificationmaterial in each of the foregoing examples and embodiments recited inthis paragraph is a polymer containing sulfobetaine or carboxybetainerepeat units. In one embodiment, the polymeric surface modificationmaterial in each of the foregoing examples and embodiments recited inthis paragraph is a zwitterionic polymer and the zwitterionic polymer isgrafted from a silicone hydrogel material. In one embodiment, thepolymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a carboxyammoniumor sulfoammonium polymer and the carboxyammonium or sulfoammoniumpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units and the polymercontaining sulfobetaine or carboxybetaine repeat units is grafted from asilicone hydrogel material. In one embodiment, the article of each ofthe foregoing examples and embodiments in this paragraph is a contactlens.

In some embodiments, it may be preferable to also have a maximum depthfor the penetration of the surface modification polymer into the bulkmaterial. Without being bound to any theory, limiting the penetration ofthe surface modification polymer may limit the degree to which thesurface modification changes the bulk properties of the lens, such aswater content and oxygen permeability. Thus, for example, it may bedesirable to have a surface modification that does not change these bulkproperties. In one embodiment, the surface modification polymer extendsa maximum penetration depth of 1%, 2%, 5%, 10%, 15%, 20%, 30%, or 45%below the surface of the lens in a direction normal to the surface ofthe lens. Stated differently, in certain embodiments, the penetrationdepth of the surface modification polymer does not does not exceed 45%of the thickness of the lens measured from the surface and in adirection normal to the surface of the lens. In certain embodiments, thepenetration depth of the surface modification polymer does not does notexceed 30% of the thickness of the lens measured from the surface and ina direction normal to the surface of the lens. In certain embodiments,the penetration depth of the surface modification polymer does not doesnot exceed 20% of the thickness of the lens measured from the surfaceand in a direction normal to the surface of the lens. In certainembodiments, the penetration depth of the surface modification polymerdoes not does not exceed 15% of the thickness of the lens measured fromthe surface and in a direction normal to the surface of the lens. Iincertain embodiments, the penetration depth of the surface modificationpolymer does not does not exceed 10% of the thickness of the lensmeasured from the surface and in a direction normal to the surface ofthe lens. In certain embodiments, the penetration depth of the surfacemodification polymer does not does not exceed 5% of the thickness of thelens measured from the surface and in a direction normal to the surfaceof the lens. In certain embodiments, the penetration depth of thesurface modification polymer does not does not exceed 2% of thethickness of the lens measured from the surface and in a directionnormal to the surface of the lens. In certain embodiments, thepenetration depth of the surface modification polymer does not does notexceed 1% of the thickness of the lens measured from the surface and ina direction normal to the surface of the lens. Thus, for example, thesurface modification polymer may extend a maximum penetration depth offrom about 1% to about 5%, from about 1% to about 10%, from about 1% toabout 20%, or from about 1% to about 30%. By way of another example, thesurface modification polymer may extend a maximum penetration depth offrom about 2% to about 5%, from about 2% to about 15%, from about 2% toabout 30%, or from about 2% to about 45%. By way of another example, thesurface modification polymer may extend a maximum penetration depth offrom about 5% to about 10%, from about 5% to about 20%, from about 5% toabout 30%, or from about 5% to about 45%. By way of another example, thesurface modification polymer may extend a maximum penetration depth offrom about 0.25% to about 2%, from about 0.25% to about 1.5%, from about0.25% to about 1%, or from about 0.25% to about 0.75%. By way of anotherexample, the surface modification polymer may extend a maximumpenetration depth of from about 0.5% to about 2%, from about 0.5% toabout 1.5%, from about 0.5% to about 1%, or from about 0.5% to about0.75%. In one embodiment, the polymeric surface modification material ineach of the foregoing embodiments and examples recited in this paragraphis a zwitterionic polymer. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing carboxyammonium orsulfoammonium repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a zwitterionic polymer and the zwitterionicpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a carboxyammoniumor sulfoammonium polymer and the carboxyammonium or sulfoammoniumpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units and the polymercontaining sulfobetaine or carboxybetaine repeat units is grafted from asilicone hydrogel material. In one embodiment, the article of each ofthe foregoing examples and embodiments in this paragraph is a contactlens.

In one embodiment, the penetration depth of the surface modificationpolymer into the bulk is greater than about 0.1 microns and less thanabout 100 microns. The penetration depth may be measured on a dehydratedlens or on a hydrated lens. Thus, for example, penetration depth can beat least about 0.1 microns, about 0.25 microns, about 0.5 microns, about0.75 microns, about 1 microns, about 5 microns, about 10 microns, about15 microns, about 20 microns, about 25 microns, about 30 microns, about35 microns, about 40 microns, about 45 microns, about 50 microns, about55 microns, about 60 microns, about 65 microns, about 70 microns, about75 microns, about 80 microns, about 85 microns, about 90 microns, orabout 95 microns. In another embodiment, for example, the penetrationdepth of the surface modification polymer is greater than about 0.1microns and less than about 2 microns (e.g., from about 0.1 microns toabout 1.5 microns; from about 0.1 microns to about 1 micron, or fromabout 0.1 microns to about 75 microns). In another embodiment, forexample, the penetration depth of the surface modification polymer isgreater than about 0.25 microns and less than about 2 microns (e.g.,from about 0.25 microns to about 1.5 microns; from about 0.25 microns toabout 1 micron, or from about 0.25 microns to about 75 microns). Inanother embodiment, for example, the penetration depth of the surfacemodification polymer is greater than about 0.5 microns and less thanabout 2 microns (e.g., from about 0.5 microns to about 1.5 microns; fromabout 0.5 microns to about 1 micron, or from about 0.5 microns to about75 microns). In another embodiment, for example, the penetration depthof the surface modification polymer is greater than about 0.5 micronsand less than about 50 microns (e.g., from about 1 microns to about 45microns; from about 5 microns to about 35 microns, or from about 10microns to about 25 microns). In another embodiment, the penetrationdepth of the surface modification polymer is greater than about 2microns and less than about 30 microns (e.g., from about 5 microns toabout 25 microns, from about 10 microns to about 20 microns, or fromabout 12.5 microns to about 17.5 microns). In another embodiment, thepenetration depth of the surface modification polymer is greater thanabout 5 microns and less than about 20 microns (e.g., from about 10microns to about 15 microns). In one embodiment, the polymeric surfacemodification material in each of the foregoing embodiments and examplesrecited in this paragraph is a zwitterionic polymer. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining carboxyammonium or sulfoammonium repeat units. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is apolymer containing sulfobetaine or carboxybetaine repeat units. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is azwitterionic polymer and the zwitterionic polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a carboxyammonium or sulfoammonium polymerand the carboxyammonium or sulfoammonium polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units and the polymer containing sulfobetaine orcarboxybetaine repeat units is grafted from a silicone hydrogelmaterial. In one embodiment, the article of each of the foregoingexamples and embodiments in this paragraph is a contact lens.

In some embodiments, it is preferable to have at least a minimum mass ofthe surface modification polymer on or within the surface of the medicaldevice. Creating a minimum mass reduces the likelihood that defectswithout modification are found or that the surface modification isremoved from a portion of the device when stressed, washed withchemicals, or rubbed. In one embodiment, for example, the minimum weightpercentage of the surface modification is at least 0.1%, at least 0.5%,at least 1%, at least 5%, or at least 10% of the total weight of thearticle. Thus, for example, the minimum weight percentage of the surfacemodification may be at least 0.1%, at least 0.5%, at least 1%, at least1.5%, at least 2.0%, at least 2.5%, at least 3.0%, at least 3.5%, atleast 4.0%, at least 4.5%, at least 5.0%, at least 5.5%, at least 6.5%,at least 7.0%, at least 7.5%, at least 8.0%, at least 8.5%, at least9.0%, at least 9.5%, or at least 10%, of the total weight of thearticle. In one embodiment, the polymeric surface modification materialin each of the foregoing embodiments and examples recited in thisparagraph is a zwitterionic polymer. In one embodiment, the polymericsurface modification material in each of the foregoing examples andembodiments recited in this paragraph is a polymer containingcarboxyammonium or sulfoammonium repeat units. In one embodiment, thepolymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is azwitterionic polymer and the zwitterionic polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a carboxyammonium or sulfoammonium polymerand the carboxyammonium or sulfoammonium polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units and the polymer containing sulfobetaine orcarboxybetaine repeat units is grafted from a silicone hydrogelmaterial. In one embodiment, the article of each of the foregoingexamples and embodiments in this paragraph is a contact lens.

This mass fraction may be assessed, for example, by elemental analysis,XPS or SEM-EDS. Other quantitative methods include: Gravimetry, wherethe sample is dissolved and then the element of interest is precipitatedand its mass measured or the element of interest is volatilized and themass loss is measured; and optical atomic spectroscopy, such as flameatomic absorption, graphite furnace atomic absorption, and inductivelycoupled plasma atomic emission, which probe the outer electronicstructure of atoms.

The concentration of the modified polymers can also be determined by acharacteristic elemental analysis method. For sulfobetainepolymer-modified lenses, for example, a total sulfur analysis may bemeasured using a combustion and gas chromatography (GC) method. Formodified polymer without any characteristic element, a broad surveyanalysis of total elements, such as C, N, H, S, and O, of both modifiedand un-modified lenses can be performed by combustion/GC, Coulometric,or chemical titration methods, and the relative modificationconcentration can be measured.

If a unique element exists in the surface modification polymer and notin the lens, the mass fraction of that element in the lens may bemeasured. This mass fraction of the single element may then be used tocalculate the mass fraction of the surface modification polymer based onthe mass percentage of that element in the surface modification polymer.For instance, for sulfobetaine, the mass fraction of sulfur in the totallens (or other article) may be measured experimentally. The massfraction of sulfur within a homopolymer of sulfobetaine is known to be0.109 g sulfur/g sulfobetaine, and therefore the mass fraction of thesulfobetaine in the article can be calculated based on the mass fractionof sulfur in the lens divided by 0.109 g sulfur/g sulfobetaine. In oneembodiment, the total sulfur concentration in a contact lens, analyzedby ICP method, is 1 μg, 5 μg, 10 μg, 50 μg, 100 μg, 500 μg, 1 mg, 20 mg,or 50 mg/g contact lens; more preferably, the sulfur concentration is1-20 mg/g contact lens.

Where the modified article is a contact lens, the modified lenspreferably has an oxygen permeability greater than about 50 barrers.More preferably, the lens has an oxygen permeability greater than about90 barrers. Still more preferably, the lens has an oxygen permeabilitygreater than about 150 barrers. Still more preferably, the lens has anoxygen permeability greater than about 160 barrers. Thus, in variousembodiments, the modified lens can have an oxygen permeability of about55, about 60, about 65, about 70, about 75, about 80, about 85, about90, about 95, about 100, about 105, about 110, about 115, about 120,about 125, about 130, about 135, about 140, about 145, about 150, about155, about 160, about 165, about 170, about 175, about 180, about 185,about 190, about 195, or about 200 barrers. In one embodiment, thepolymeric surface modification material in each of the foregoingembodiments and examples recited in this paragraph is a zwitterionicpolymer. In one embodiment, the polymeric surface modification materialin each of the foregoing examples and embodiments recited in thisparagraph is a polymer containing carboxyammonium or sulfoammoniumrepeat units. In one embodiment, the polymeric surface modificationmaterial in each of the foregoing examples and embodiments recited inthis paragraph is a polymer containing sulfobetaine or carboxybetainerepeat units. In one embodiment, the polymeric surface modificationmaterial in each of the foregoing examples and embodiments recited inthis paragraph is a zwitterionic polymer and the zwitterionic polymer isgrafted from a silicone hydrogel material. In one embodiment, thepolymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a carboxyammoniumor sulfoammonium polymer and the carboxyammonium or sulfoammoniumpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units and the polymercontaining sulfobetaine or carboxybetaine repeat units is grafted from asilicone hydrogel material.

Articles including polymeric surface modifications as described hereinpreferably exhibit a static contact angle of less than 30 degrees. Forexample, in one embodiment modified surfaces of articles describedherein exhibit a static contact angle of less than 25 degrees, less than20 degrees, or less than 15 degrees. In one preferred embodiment,modified surfaces of articles described herein exhibit a static contactangle of less than 10 degrees; more preferably less than 5 degrees;still more preferably completely wettable, that is, unable to bemeasured by a sessile drop method and having no interaction with thesurface using a captive bubble method. In one embodiment, the polymericsurface modification material in each of the foregoing embodiments andexamples recited in this paragraph is a zwitterionic polymer. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is apolymer containing carboxyammonium or sulfoammonium repeat units. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is apolymer containing sulfobetaine or carboxybetaine repeat units. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is azwitterionic polymer and the zwitterionic polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a carboxyammonium or sulfoammonium polymerand the carboxyammonium or sulfoammonium polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units and the polymer containing sulfobetaine orcarboxybetaine repeat units is grafted from a silicone hydrogelmaterial. In one embodiment, the article of each of the foregoingexamples and embodiments in this paragraph is a contact lens.

Articles including polymeric surface modifications as described hereinpreferably exhibit a reduction in static contact angle by greater than 5degrees, greater than 10 degrees, greater than 15 degrees, greater than20 degrees, greater than 25 degrees, greater than 30 degrees, greaterthan 35 degrees, greater than 40 degrees, greater than 45 degrees,greater than 50 degrees, greater than 55 degrees, or greater than 60degrees. In one embodiment, the polymeric surface modification materialin each of the foregoing embodiments and examples recited in thisparagraph is a zwitterionic polymer. In one embodiment, the polymericsurface modification material in each of the foregoing examples andembodiments recited in this paragraph is a polymer containingcarboxyammonium or sulfoammonium repeat units. In one embodiment, thepolymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is azwitterionic polymer and the zwitterionic polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a carboxyammonium or sulfoammonium polymerand the carboxyammonium or sulfoammonium polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units and the polymer containing sulfobetaine orcarboxybetaine repeat units is grafted from a silicone hydrogelmaterial. In one embodiment, the article of each of the foregoingexamples and embodiments in this paragraph is a contact lens.

Articles including polymeric surface modifications as described hereinpreferably exhibit an advancing contact angle of less than 30 degrees.For example, in one embodiment modified surfaces of articles describedherein exhibit an advancing contact angle of less than 25 degrees, lessthan 20 degrees, or less than 19 degrees. In one embodiment, thepolymeric surface modification material in each of the foregoingembodiments and examples recited in this paragraph is a zwitterionicpolymer. In one embodiment, the polymeric surface modification materialin each of the foregoing examples and embodiments recited in thisparagraph is a polymer containing carboxyammonium or sulfoammoniumrepeat units. In one embodiment, the polymeric surface modificationmaterial in each of the foregoing examples and embodiments recited inthis paragraph is a polymer containing sulfobetaine or carboxybetainerepeat units. In one embodiment, the polymeric surface modificationmaterial in each of the foregoing examples and embodiments recited inthis paragraph is a zwitterionic polymer and the zwitterionic polymer isgrafted from a silicone hydrogel material. In one embodiment, thepolymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a carboxyammoniumor sulfoammonium polymer and the carboxyammonium or sulfoammoniumpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units and the polymercontaining sulfobetaine or carboxybetaine repeat units is grafted from asilicone hydrogel material. In one embodiment, the article of each ofthe foregoing examples and embodiments in this paragraph is a contactlens.

Articles including polymeric surface modifications as described hereinpreferably exhibit a reduction in advancing contact angle relative tounmodified lenses by greater than 5 degrees, greater than 10 degrees,greater than 15 degrees, greater than 20 degrees, greater than 25degrees, greater than 30 degrees, greater than 35 degrees, greater than40 degrees, greater than 45 degrees, greater than 50 degrees, greaterthan 55 degrees, or greater than 60 degrees. In one embodiment, thepolymeric surface modification material in each of the foregoingembodiments and examples recited in this paragraph is a zwitterionicpolymer. In one embodiment, the polymeric surface modification materialin each of the foregoing examples and embodiments recited in thisparagraph is a polymer containing carboxyammonium or sulfoammoniumrepeat units. In one embodiment, the polymeric surface modificationmaterial in each of the foregoing examples and embodiments recited inthis paragraph is a polymer containing sulfobetaine or carboxybetainerepeat units. In one embodiment, the polymeric surface modificationmaterial in each of the foregoing examples and embodiments recited inthis paragraph is a zwitterionic polymer and the zwitterionic polymer isgrafted from a silicone hydrogel material. In one embodiment, thepolymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a carboxyammoniumor sulfoammonium polymer and the carboxyammonium or sulfoammoniumpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units and the polymercontaining sulfobetaine or carboxybetaine repeat units is grafted from asilicone hydrogel material. In one embodiment, the article of each ofthe foregoing examples and embodiments in this paragraph is a contactlens.

Articles including polymeric surface modifications as described hereinpreferably have a coefficient of friction of less than about 0.1, lessthan about 0.05, or less than about 0.02. Thus, for example, thearticles may have a coefficient of friction of about 0.1, about 0.09,about 0.08, about 0.07, about 0.06, about 0.05, about 0.04, about 0.03,about 0.02, about 0.01, or less. In one embodiment, the polymericsurface modification material in each of the foregoing embodiments andexamples recited in this paragraph is a zwitterionic polymer. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is apolymer containing carboxyammonium or sulfoammonium repeat units. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is apolymer containing sulfobetaine or carboxybetaine repeat units. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is azwitterionic polymer and the zwitterionic polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a carboxyammonium or sulfoammonium polymerand the carboxyammonium or sulfoammonium polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units and the polymer containing sulfobetaine orcarboxybetaine repeat units is grafted from a silicone hydrogelmaterial. In one embodiment, the article of each of the foregoingexamples and embodiments in this paragraph is a contact lens.

In a particular embodiment, articles including polymeric surfacemodifications as described herein have a static contact angle of lessthan 30 and an oxygen permeability of greater than 80. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a static contact angle of lessthan 25 and an oxygen permeability of greater than 80. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a static contact angle of lessthan 20 and an oxygen permeability of greater than 80. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a static contact angle of lessthan 15 and an oxygen permeability of greater than 80. In oneembodiment, the polymeric surface modification material in each of theforegoing embodiments and examples recited in this paragraph is azwitterionic polymer. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing carboxyammonium orsulfoammonium repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a zwitterionic polymer and the zwitterionicpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a carboxyammoniumor sulfoammonium polymer and the carboxyammonium or sulfoammoniumpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units and the polymercontaining sulfobetaine or carboxybetaine repeat units is grafted from asilicone hydrogel material. In one embodiment, the article of each ofthe foregoing examples and embodiments in this paragraph is a contactlens.

In a particular embodiment, articles including polymeric surfacemodifications as described herein have a static contact angle of lessthan 30 and an oxygen permeability of greater than 100. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a static contact angle of lessthan 25 and an oxygen permeability of greater than 100. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a static contact angle of lessthan 20 and an oxygen permeability of greater than 100. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a static contact angle of lessthan 15 and an oxygen permeability of greater than 100. In oneembodiment, the polymeric surface modification material in each of theforegoing embodiments and examples recited in this paragraph is azwitterionic polymer. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing carboxyammonium orsulfoammonium repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a zwitterionic polymer and the zwitterionicpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a carboxyammoniumor sulfoammonium polymer and the carboxyammonium or sulfoammoniumpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units and the polymercontaining sulfobetaine or carboxybetaine repeat units is grafted from asilicone hydrogel material. In one embodiment, the article of each ofthe foregoing examples and embodiments in this paragraph is a contactlens.

In a particular embodiment, articles including polymeric surfacemodifications as described herein have an advancing contact angle ofless than 30 and an oxygen permeability of greater than 80. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have an advancing contact angle ofless than 25 and an oxygen permeability of greater than 80. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have an advancing contact angle ofless than 20 and an oxygen permeability of greater than 80. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have an advancing contact angle ofless than 15 and an oxygen permeability of greater than 80. In oneembodiment, the polymeric surface modification material in each of theforegoing embodiments and examples recited in this paragraph is azwitterionic polymer. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing carboxyammonium orsulfoammonium repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a zwitterionic polymer and the zwitterionicpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a carboxyammoniumor sulfoammonium polymer and the carboxyammonium or sulfoammoniumpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units and the polymercontaining sulfobetaine or carboxybetaine repeat units is grafted from asilicone hydrogel material. In one embodiment, the article of each ofthe foregoing examples and embodiments in this paragraph is a contactlens.

In a particular embodiment, articles including polymeric surfacemodifications as described herein have an advancing contact angle ofless than 30 and an oxygen permeability of greater than 100. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have an advancing contact angle ofless than 25 and an oxygen permeability of greater than 100. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have an advancing contact angle ofless than 20 and an oxygen permeability of greater than 100. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have an advancing contact angle ofless than 15 and an oxygen permeability of greater than 100. In oneembodiment, the polymeric surface modification material in each of theforegoing embodiments and examples recited in this paragraph is azwitterionic polymer. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing carboxyammonium orsulfoammonium repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a zwitterionic polymer and the zwitterionicpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a carboxyammoniumor sulfoammonium polymer and the carboxyammonium or sulfoammoniumpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units and the polymercontaining sulfobetaine or carboxybetaine repeat units is grafted from asilicone hydrogel material. In one embodiment, the article of each ofthe foregoing examples and embodiments in this paragraph is a contactlens.

In a particular embodiment, articles including polymeric surfacemodifications as described herein have a coefficient of friction of lessthan 0.1 and an oxygen permeability of greater than 80. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a coefficient of friction of lessthan 0.05 and an oxygen permeability of greater than 80. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a coefficient of friction of lessthan 0.02 and an oxygen permeability of greater than 80. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a coefficient of friction of lessthan 0.1 and an oxygen permeability of greater than 100. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a coefficient of friction of lessthan 0.05 and an oxygen permeability of greater than 100. In anotherparticular embodiment, articles including polymeric surfacemodifications as described herein have a coefficient of friction of lessthan 0.02 and an oxygen permeability of greater than 100. In oneembodiment, the polymeric surface modification material in each of theforegoing embodiments and examples recited in this paragraph is azwitterionic polymer. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing carboxyammonium orsulfoammonium repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a zwitterionic polymer and the zwitterionicpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a carboxyammoniumor sulfoammonium polymer and the carboxyammonium or sulfoammoniumpolymer is grafted from a silicone hydrogel material. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining sulfobetaine or carboxybetaine repeat units and the polymercontaining sulfobetaine or carboxybetaine repeat units is grafted from asilicone hydrogel material. In one embodiment, the article of each ofthe foregoing examples and embodiments in this paragraph is a contactlens.

Where the article is a contact lens, for example, a patient using thearticle will exhibit a tear-film break up time of greater than 10seconds, more preferably greater than 15 seconds, more preferablygreater than 20 seconds. In one embodiment, for example, the tear-filmbreak up time for an article in use in a patient is from about 7.5seconds to about 20 seconds. In another embodiment, for example, thetear-film break up time for an article in use in a patient is from about10 seconds to about 20 seconds. In another embodiment, for example, thetear-film break up time for an article in use in a patient is from about10 seconds to about 15 seconds. In another embodiment, for example, thetear-film break up time for an article in use in a patient is from about15 seconds to about 20 seconds. In one embodiment, the polymeric surfacemodification material in each of the foregoing embodiments and examplesrecited in this paragraph is a zwitterionic polymer. In one embodiment,the polymeric surface modification material in each of the foregoingexamples and embodiments recited in this paragraph is a polymercontaining carboxyammonium or sulfoammonium repeat units. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is apolymer containing sulfobetaine or carboxybetaine repeat units. In oneembodiment, the polymeric surface modification material in each of theforegoing examples and embodiments recited in this paragraph is azwitterionic polymer and the zwitterionic polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a carboxyammonium or sulfoammonium polymerand the carboxyammonium or sulfoammonium polymer is grafted from asilicone hydrogel material. In one embodiment, the polymeric surfacemodification material in each of the foregoing examples and embodimentsrecited in this paragraph is a polymer containing sulfobetaine orcarboxybetaine repeat units and the polymer containing sulfobetaine orcarboxybetaine repeat units is grafted from a silicone hydrogelmaterial. In one embodiment, the article of each of the foregoingexamples and embodiments in this paragraph is a contact lens.

In another particular embodiment, the polymeric surface modificationmaterial is a zwitterionic polymer, the advancing contact angle is lessthan about 30 degrees, and exhibits a tear film break-up time in use ofgreater than 10 seconds. In another particular embodiment, the polymericsurface modification material is a zwitterionic polymer, the advancingcontact angle is less than about 25 degrees, and exhibits a tear filmbreak-up time in use of greater than 10 seconds. In another particularembodiment, the polymeric surface modification material is azwitterionic polymer, the advancing contact angle is less than about 20degrees, and exhibits a tear film break-up time in use of greater than10 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 19 degrees, and exhibits a tear film break-uptime in use of greater than 10 seconds. In another particularembodiment, the polymeric surface modification material is azwitterionic polymer, the advancing contact angle is less than about 30degrees, and exhibits a tear film break-up time in use of greater than15 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 25 degrees, and exhibits a tear film break-uptime in use of greater than 15 seconds. In another particularembodiment, the polymeric surface modification material is azwitterionic polymer, the advancing contact angle is less than about 20degrees, and exhibits a tear film break-up time in use of greater than15 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 19 degrees, and exhibits a tear film break-uptime in use of greater than 15 seconds. In another particularembodiment, the polymeric surface modification material is azwitterionic polymer, the advancing contact angle is less than about 30degrees, and exhibits a tear film break-up time in use of greater than20 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 25 degrees, and exhibits a tear film break-uptime in use of greater than 20 seconds. In another particularembodiment, the polymeric surface modification material is azwitterionic polymer, the advancing contact angle is less than about 20degrees, and exhibits a tear film break-up time in use of greater than20 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 19 degrees, and exhibits a tear film break-uptime in use of greater than 20 seconds. In one embodiment, the articleof each of the foregoing examples and embodiments in this paragraph is acontact lens.

In another particular embodiment, the polymeric surface modificationmaterial is a zwitterionic polymer, the coefficient of friction is lessthan 0.1, and exhibits a tear film break-up time in use of greater than10 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the coefficient offriction is less than 0.05, and exhibits a tear film break-up time inuse of greater than 10 seconds. In another particular embodiment, thepolymeric surface modification material is a zwitterionic polymer, thecoefficient of friction is less than 0.02, and exhibits a tear filmbreak-up time in use of greater than 10 seconds. In another particularembodiment, the polymeric surface modification material is azwitterionic polymer, the coefficient of friction is less than 0.1, andexhibits a tear film break-up time in use of greater than 15 seconds. Inanother particular embodiment, the polymeric surface modificationmaterial is a zwitterionic polymer, the coefficient of friction is lessthan 0.05, and exhibits a tear film break-up time in use of greater than15 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the coefficient offriction is less than 0.02, and exhibits a tear film break-up time inuse of greater than 15 seconds. In another particular embodiment, thepolymeric surface modification material is a zwitterionic polymer, thecoefficient of friction is less than 0.1, and exhibits a tear filmbreak-up time in use of greater than 20 seconds. In another particularembodiment, the polymeric surface modification material is azwitterionic polymer, the coefficient of friction is less than 0.05, andexhibits a tear film break-up time in use of greater than 20 seconds. Inanother particular embodiment, the polymeric surface modificationmaterial is a zwitterionic polymer, the coefficient of friction is lessthan 0.02, and exhibits a tear film break-up time in use of greater than20 seconds. In one embodiment, the article of each of the foregoingexamples and embodiments in this paragraph is a contact lens.

In another particular embodiment, the polymeric surface modificationmaterial is a zwitterionic polymer, the advancing contact angle is lessthan 30 degrees, the coefficient of friction is less than 0.1, andexhibits a tear-film break-up time in use of greater than 10 seconds. Inanother particular embodiment, the polymeric surface modificationmaterial is a zwitterionic polymer, the advancing contact angle is lessthan 25 degrees, the coefficient of friction is less than 0.1, andexhibits a tear-film break-up time in use of greater than 10 seconds. Inanother particular embodiment, the polymeric surface modificationmaterial is a zwitterionic polymer, the advancing contact angle is lessthan 20 degrees, the coefficient of friction is less than 0.1, andexhibits a tear-film break-up time in use of greater than 10 seconds. Inanother particular embodiment, the polymeric surface modificationmaterial is a zwitterionic polymer, the advancing contact angle is lessthan 19 degrees, the coefficient of friction is less than 0.1, andexhibits a tear-film break-up time in use of greater than 10 seconds. Insome of these embodiments, the coefficient of friction is less than0.05, or less than 0.02. In these and other embodiments, the tear-filmbreak-up time in use may be greater than 15 seconds, or greater than 20seconds. In one embodiment, the article of each of the foregoingexamples and embodiments in this paragraph is a contact lens.

In another particular embodiment, the polymeric surface modification iszwitterionic polymer, the advancing contact angle is less than about 30degrees, and the surface modification has a depth of penetration of atleast about 0.1% of the thickness of the lens below the surface of thelens in a direction normal to the surface of the lens. In thisembodiment, for example, the depth of penetration can be 0.1%, 0.2%,0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or 45% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens. In another particular embodiment, the polymeric surfacemodification is zwitterionic polymer, the advancing contact angle isless than about 25 degrees, and the surface modification has a depth ofpenetration of at least about 0.1% of the thickness of the lens belowthe surface of the lens in a direction normal to the surface of thelens. In this embodiment, for example, the depth of penetration can be0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or 45% of the thicknessof the lens below the surface of the lens in a direction normal to thesurface of the lens. In another particular embodiment, the polymericsurface modification is zwitterionic polymer, the advancing contactangle is less than about 20 degrees, and the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens. In this embodiment, for example, the depth of penetration canbe 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or 45% of thethickness of the lens below the surface of the lens in a directionnormal to the surface of the lens. In another particular embodiment, thepolymeric surface modification is zwitterionic polymer, the advancingcontact angle is less than about 19 degrees, and the surfacemodification has a depth of penetration of at least about 0.1% of thethickness of the lens below the surface of the lens in a directionnormal to the surface of the lens. In this embodiment, for example, thedepth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%,40% or 45% of the thickness of the lens below the surface of the lens ina direction normal to the surface of the lens. In one embodiment, thearticle of each of the foregoing examples and embodiments in thisparagraph is a contact lens.

In another particular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.1, andthe surface modification has a depth of penetration of at least about0.1% of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.05, andthe surface modification has a depth of penetration of at least about0.1% of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.02, andthe surface modification has a depth of penetration of at least about0.1% of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In oneembodiment, the article of each of the foregoing examples andembodiments in this paragraph is a contact lens.

In another particular embodiment, the polymeric surface modification iszwitterionic polymer, the surface modification has a depth ofpenetration of at least about 0.1% of the thickness of the lens belowthe surface of the lens in a direction normal to the surface of thelens, and in use exhibits a tear-film break-up time of greater than 10seconds. In this embodiment, for example, the depth of penetration canbe 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or 45% of thethickness of the lens below the surface of the lens in a directionnormal to the surface of the lens. In another particular embodiment, thepolymeric surface modification is zwitterionic polymer, the surfacemodification has a depth of penetration of at least about 0.1% of thethickness of the lens below the surface of the lens in a directionnormal to the surface of the lens, and in use exhibits a tear-filmbreak-up time of greater than 15 seconds. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the surface modification has a depth ofpenetration of at least about 0.1% of the thickness of the lens belowthe surface of the lens in a direction normal to the surface of thelens, and in use exhibits a tear-film break-up time of greater than 20seconds. In this embodiment, for example, the depth of penetration canbe 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or 45% of thethickness of the lens below the surface of the lens in a directionnormal to the surface of the lens. In one embodiment, the article ofeach of the foregoing examples and embodiments in this paragraph is acontact lens.

In another particular embodiment, the polymeric surface modificationmaterial is a zwitterionic polymer, the advancing contact angle is lessthan 30 degrees, the coefficient of friction is less than 0.1, and thesurface modification has a depth of penetration of at least about 0.1%of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens. In another particularembodiment, the polymeric surface modification material is azwitterionic polymer, the advancing contact angle is less than 25degrees, the coefficient of friction is less than 0.1, and the surfacemodification has a depth of penetration of at least about 0.1% of thethickness of the lens below the surface of the lens in a directionnormal to the surface of the lens. In another particular embodiment, thepolymeric surface modification material is a zwitterionic polymer, theadvancing contact angle is less than 20 degrees, the coefficient offriction is less than 0.1, and the surface modification has a depth ofpenetration of at least about 0.1% of the thickness of the lens belowthe surface of the lens in a direction normal to the surface of thelens. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than 19 degrees, the coefficient of friction is less than0.1, and the surface modification has a depth of penetration of at leastabout 0.1% of the thickness of the lens below the surface of the lens ina direction normal to the surface of the lens. In some of theseembodiments, for example, the coefficient of friction is less than 0.05,or less than 0.02. In these and other embodiments, for example, thedepth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%,40% or 45% of the thickness of the lens below the surface of the lens ina direction normal to the surface of the lens. In one embodiment, thearticle of each of the foregoing examples and embodiments in thisparagraph is a contact lens.

In another particular embodiment, the polymeric surface modificationmaterial is a zwitterionic polymer, the advancing contact angle is lessthan about 30 degrees, the surface modification has a depth ofpenetration of at least about 0.1% of the thickness of the lens belowthe surface of the lens in a direction normal to the surface of thelens, and exhibits a tear film break-up time in use of greater than 10seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 25 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than10 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 20 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than10 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 19 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than10 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 30 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than15 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 25 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than15 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 20 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than15 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 19 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than15 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 30 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than20 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 25 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than20 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 20 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than20 seconds. In another particular embodiment, the polymeric surfacemodification material is a zwitterionic polymer, the advancing contactangle is less than about 19 degrees, the surface modification has adepth of penetration of at least about 0.1% of the thickness of the lensbelow the surface of the lens in a direction normal to the surface ofthe lens, and exhibits a tear film break-up time in use of greater than20 seconds. In some of these embodiments, for example, the depth ofpenetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or45% of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens. In one embodiment, thearticle of each of the foregoing examples and embodiments in thisparagraph is a contact lens.

In another particular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.1, thesurface modification has a depth of penetration of at least about 0.1%of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens, and exhibits a tear filmbreak-up time in use of greater than 10 seconds. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.05, thesurface modification has a depth of penetration of at least about 0.1%of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens, and exhibits a tear filmbreak-up time in use of greater than 10 seconds. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.02, thesurface modification has a depth of penetration of at least about 0.1%of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens, and exhibits a tear filmbreak-up time in use of greater than 10 seconds. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.1, thesurface modification has a depth of penetration of at least about 0.1%of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens, and exhibits a tear filmbreak-up time in use of greater than 15 seconds. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.05, thesurface modification has a depth of penetration of at least about 0.1%of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens, and exhibits a tear filmbreak-up time in use of greater than 15 seconds. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.02, thesurface modification has a depth of penetration of at least about 0.1%of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens, and exhibits a tear filmbreak-up time in use of greater than 15 seconds. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.1, thesurface modification has a depth of penetration of at least about 0.1%of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens, and exhibits a tear filmbreak-up time in use of greater than 20 seconds. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.05, thesurface modification has a depth of penetration of at least about 0.1%of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens, and exhibits a tear filmbreak-up time in use of greater than 20 seconds. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the coefficient of friction is less than 0.02, thesurface modification has a depth of penetration of at least about 0.1%of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens, and exhibits a tear filmbreak-up time in use of greater than 20 seconds. In this embodiment, forexample, the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In oneembodiment, the article of each of the foregoing examples andembodiments in this paragraph is a contact lens.

In another particular embodiment, the polymeric surface modification iszwitterionic polymer, the advancing contact angle is less than about 30degrees, the coefficient of friction is less than 0.1, the surfacemodification has a depth of penetration of at least about 0.1% of thethickness of the lens below the surface of the lens in a directionnormal to the surface of the lens, and exhibits a tear film break-uptime in use of greater than 10 seconds. In various embodiments, forexample, the contact angle can be less than about 25 degrees, less thanabout 20 degrees, or less than about 19 degrees, and/or the depth ofpenetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or45% of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens. In another particularembodiment, the polymeric surface modification is zwitterionic polymer,the advancing contact angle is less than about 30 degrees, thecoefficient of friction is less than 0.05, the surface modification hasa depth of penetration of at least about 0.1% of the thickness of thelens below the surface of the lens in a direction normal to the surfaceof the lens, and exhibits a tear film break-up time in use of greaterthan 10 seconds. In various embodiments, for example, the contact anglecan be less than about 25 degrees, less than about 20 degrees, or lessthan about 19 degrees, and/or the depth of penetration can be 0.1%,0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or 45% of the thickness ofthe lens below the surface of the lens in a direction normal to thesurface of the lens. In another particular embodiment, the polymericsurface modification is zwitterionic polymer, the advancing contactangle is less than about 30 degrees, the coefficient of friction is lessthan 0.02, the surface modification has a depth of penetration of atleast about 0.1% of the thickness of the lens below the surface of thelens in a direction normal to the surface of the lens, and exhibits atear film break-up time in use of greater than 10 seconds. In variousembodiments, for example, the contact angle can be less than about 25degrees, less than about 20 degrees, or less than about 19 degrees,and/or the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the advancing contact angle is less than about 30degrees, the coefficient of friction is less than 0.1, the surfacemodification has a depth of penetration of at least about 0.1% of thethickness of the lens below the surface of the lens in a directionnormal to the surface of the lens, and exhibits a tear film break-uptime in use of greater than 15 seconds. In various embodiments, forexample, the contact angle can be less than about 25 degrees, less thanabout 20 degrees, or less than about 19 degrees, and/or the depth ofpenetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or45% of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens. In another particularembodiment, the polymeric surface modification is zwitterionic polymer,the advancing contact angle is less than about 30 degrees, thecoefficient of friction is less than 0.05, the surface modification hasa depth of penetration of at least about 0.1% of the thickness of thelens below the surface of the lens in a direction normal to the surfaceof the lens, and exhibits a tear film break-up time in use of greaterthan 15 seconds. In various embodiments, for example, the contact anglecan be less than about 25 degrees, less than about 20 degrees, or lessthan about 19 degrees, and/or the depth of penetration can be 0.1%,0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or 45% of the thickness ofthe lens below the surface of the lens in a direction normal to thesurface of the lens. In another particular embodiment, the polymericsurface modification is zwitterionic polymer, the advancing contactangle is less than about 30 degrees, the coefficient of friction is lessthan 0.02, the surface modification has a depth of penetration of atleast about 0.1% of the thickness of the lens below the surface of thelens in a direction normal to the surface of the lens, and exhibits atear film break-up time in use of greater than 15 seconds. In variousembodiments, for example, the contact angle can be less than about 25degrees, less than about 20 degrees, or less than about 19 degrees,and/or the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In anotherparticular embodiment, the polymeric surface modification iszwitterionic polymer, the advancing contact angle is less than about 30degrees, the coefficient of friction is less than 0.1, the surfacemodification has a depth of penetration of at least about 0.1% of thethickness of the lens below the surface of the lens in a directionnormal to the surface of the lens, and exhibits a tear film break-uptime in use of greater than 20 seconds. In various embodiments, forexample, the contact angle can be less than about 25 degrees, less thanabout 20 degrees, or less than about 19 degrees, and/or the depth ofpenetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or45% of the thickness of the lens below the surface of the lens in adirection normal to the surface of the lens. In another particularembodiment, the polymeric surface modification is zwitterionic polymer,the advancing contact angle is less than about 30 degrees, thecoefficient of friction is less than 0.05, the surface modification hasa depth of penetration of at least about 0.1% of the thickness of thelens below the surface of the lens in a direction normal to the surfaceof the lens, and exhibits a tear film break-up time in use of greaterthan 20 seconds. In various embodiments, for example, the contact anglecan be less than about 25 degrees, less than about 20 degrees, or lessthan about 19 degrees, and/or the depth of penetration can be 0.1%,0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40% or 45% of the thickness ofthe lens below the surface of the lens in a direction normal to thesurface of the lens. In another particular embodiment, the polymericsurface modification is zwitterionic polymer, the advancing contactangle is less than about 30 degrees, the coefficient of friction is lessthan 0.02, the surface modification has a depth of penetration of atleast about 0.1% of the thickness of the lens below the surface of thelens in a direction normal to the surface of the lens, and exhibits atear film break-up time in use of greater than 20 seconds. In variousembodiments, for example, the contact angle can be less than about 25degrees, less than about 20 degrees, or less than about 19 degrees,and/or the depth of penetration can be 0.1%, 0.2%, 0.5%, 1%, 2%, 5%,10%, 20%, 30%, 40% or 45% of the thickness of the lens below the surfaceof the lens in a direction normal to the surface of the lens. In oneembodiment, the article of each of the foregoing examples andembodiments in this paragraph is a contact lens.

In general, grafted polymeric material may be detected in a near-surfacezone of the substrate using EDS mapping, XPS, or TOF-SIMS. The samplemay be freeze fractured in liquid nitrogen to expose thecoating/substrate interface. Fractured surface may then be coated with athin layer of Au/Pt and observed under a scanning electron microscopewith Energy Dispersive X-ray Analyser (EDAX) for element analysis.Suitable instruments include a FEI/Philips XL30 FEG ESEM. In order toassess if the polymeric material extends into the near-surface zone, atleast 25, and preferably at least 50, representative locations spacedapproximately evenly across the portion of the article carrying thegrafted polymer layer should be analyzed to identify a detectableenhancement of polymeric material in the near-surface zone. It ispreferred to measure the thickness at representative points across thelongest dimension of the portion of the article that is covered with thegrafted polymer layer.

As described in greater detail elsewhere herein, incorporation ofinitiator into the substrate enables polymeric material to be graftedfrom surface and from within near-surface zone of the substrate. Ingeneral, however, it is preferred that polymeric material not extend toofar into the substrate; thus, in one embodiment polymeric material ispresent in the near-surface zone but not at greater depths, i.e., not inthe bulk. The maximum depth to which near-surface zone extends is, atleast in part, a function of the initiator and the technique used toincorporate initiator in the substrate. Typically, however, it isgenerally preferred that lower boundary of the near-surface zone not begreater than 20 micrometers from the substrate surface as measured in adirection normal to the surface. By way of example, the lower boundarymay not be greater than 15 micrometers from the substrate surface asmeasured in a direction normal to the surface. By way of furtherexample, the lower boundary may not be greater than 10 micrometers fromthe substrate surface as measured in a direction normal to the surface.Similarly, the minimum depth of near-surface zone, i.e., the distance ofthe upper boundary from the substrate surface is, at least in part, alsoa function of the initiator and the technique used to incorporateinitiator in the substrate. Typically, however, the upper boundary willbe at least 0.1 micrometers from the substrate surface as measured in adirection normal to the surface. By way of example, the upper boundarymay be at least 0.2 micrometers from the substrate surface as measuredin a direction normal to the surface. By way of further example, theupper boundary may be at least 0.3 micrometers from the substratesurface as measured in a direction normal to the surface.

Because polymeric material may be grafted from the surface and fromwithin the near-surface zone of the substrate, the original surface ofsubstrate may be difficult to precisely delineate after the polymer isgrafted in such embodiments. Nevertheless, a concentration gradient ofthe grafted polymer (relative to the polymeric material of thesubstrate) may be observable with the shape of the gradient curvedepending upon such variables as the chemical composition of thesubstrate polymer, the monomer being polymerized, the polymerizationinitiator, the solvent system and polymerization reaction conditions. Insome embodiments, for example, the concentration gradient of the graftedpolymer may be approximately linear. In other embodiments, theconcentration gradient of the grafted polymer will be exponential. Inother embodiments, the concentration gradient of the grafted polymer maybe sigmoidal.

Although the shape of the concentration gradient curve for graftedpolymer (relative to the polymeric material of the substrate) may varysomewhat for each embodiment, it will generally and gradually decreaseas a function of increasing distance from the surface of the modifiedarticle in a direction normal to the surface. At a penetration depth of10% of the maximum penetration depth of the grafted polymer in oneembodiment, for example, the concentration of the grafted polymer is atleast 50% of the maximum concentration of the grafted polymer (at ornear the surface of the modified substrate). Thus, for example, theconcentration of the grafted polymer at a penetration depth of 10% ofthe maximum penetration depth may be at least 60%, at least 70%, atleast 80%, or even at least 90% of the maximum concentration of thegrafted polymer (at or near the surface of the modified substrate). Ingeneral, however, the concentration of the grafted polymer at apenetration depth of 10% of the maximum penetration depth will typicallynot exceed 95% of the maximum concentration of the grafted polymer (ator near the surface of the modified substrate). Thus, for example, theconcentration of the grafted polymer at a penetration depth of 10% ofthe maximum penetration depth will be less than 85%, less than 75%, lessthan 65%, or even less than 55% of the maximum concentration of thegrafted polymer (at or near the surface of the modified substrate). Ineach of the foregoing embodiments and examples in this paragraph, thegrafted polymer may have a minimum penetration depth of at least 50 nm,100 nm, 150 nm, 200 nm, 250 nm or more. In general, however, however,the grafted polymer may have a maximum penetration depth of 10 microns,5 microns, 1 micron, or even less than 500 nm.

At a penetration depth of 25% of the maximum penetration depth of thegrafted polymer in one embodiment, for example, the concentration of thegrafted polymer is at least 20% of the maximum concentration of thegrafted polymer (at or near the surface of the modified substrate).Thus, for example, the concentration of the grafted polymer at apenetration depth of 25% of the maximum penetration depth may be atleast 30%, at least 30%, at least 40%, at least 50%, at least 60%, atleast 70% or even at least 80% of the maximum concentration of thegrafted polymer (at or near the surface of the modified substrate). Ingeneral, however, the concentration of the grafted polymer at apenetration depth of 25% of the maximum penetration depth will typicallynot exceed 85% of the maximum concentration of the grafted polymer (ator near the surface of the modified substrate). Thus, for example, theconcentration of the grafted polymer at a penetration depth of 25% ofthe maximum penetration depth will be less than 85%, less than 75%, lessthan 65%, or even less than 55% of the maximum concentration of thegrafted polymer (at or near the surface of the modified substrate). Ineach of the foregoing embodiments and examples in this paragraph, thegrafted polymer may have a minimum penetration depth of at least 50 nm,100 nm, 150 nm, 200 nm, 250 nm or more. In general, however, however,the grafted polymer may have a maximum penetration depth of 10 microns,5 microns, 1 micron, or even less than 500 nm.

At a penetration depth of 50% of the maximum penetration depth of thegrafted polymer in one embodiment, for example, the concentration of thegrafted polymer is at least 5% of the maximum concentration of thegrafted polymer (at or near the surface of the modified substrate).Thus, for example, the concentration of the grafted polymer at apenetration depth of 50% of the maximum penetration depth may be atleast 10%, at least 20%, at least 30%, at least 40% or even at least 50%of the maximum concentration of the grafted polymer (at or near thesurface of the modified substrate). In general, however, theconcentration of the grafted polymer at a penetration depth of 50% ofthe maximum penetration depth will typically not exceed 55% of themaximum concentration of the grafted polymer (at or near the surface ofthe modified substrate). Thus, for example, the concentration of thegrafted polymer at a penetration depth of 50% of the maximum penetrationdepth will be less than 45%, less than 35%, less than 25%, or even lessthan 15% of the maximum concentration of the grafted polymer (at or nearthe surface of the modified substrate). In each of the foregoingembodiments and examples in this paragraph, the grafted polymer may havea minimum penetration depth of at least 50 nm, 100 nm, 150 nm, 200 nm,250 nm or more. In general, however, however, the grafted polymer mayhave a maximum penetration depth of 10 microns, 5 microns, 1 micron, oreven less than 500 nm.

At a penetration depth of 75% of the maximum penetration depth of thegrafted polymer in one embodiment, for example, the concentration of thegrafted polymer is at least 1% of the maximum concentration of thegrafted polymer (at or near the surface of the modified substrate).Thus, for example, the concentration of the grafted polymer at apenetration depth of 75% of the maximum penetration depth may be atleast 5%, at least 10%, at least 15%, at least 20% or even at least 25%of the maximum concentration of the grafted polymer (at or near thesurface of the modified substrate). In general, however, theconcentration of the grafted polymer at a penetration depth of 75% ofthe maximum penetration depth will typically not exceed 30% of themaximum concentration of the grafted polymer (at or near the surface ofthe modified substrate). Thus, for example, the concentration of thegrafted polymer at a penetration depth of 75% of the maximum penetrationdepth will be less than 25%, less than 20%, less than 15%, or even lessthan 10% of the maximum concentration of the grafted polymer (at or nearthe surface of the modified substrate). In each of the foregoingembodiments and examples in this paragraph, the grafted polymer may havea minimum penetration depth of at least 50 nm, 100 nm, 150 nm, 200 nm,250 nm or more. In general, however, however, the grafted polymer mayhave a maximum penetration depth of 10 microns, 5 microns, 1 micron, oreven less than 500 nm.

Medical Devices

In general, the medical device substrate material comprises any of awide range of materials selected, for example, from one or more metals,ceramics, glasses, polymers, biological tissues, living or dead, wovenand non-woven fibers, semi-metals such as silicon, and combinationsthereof. In one embodiment, the substrate is a composite of two or morematerials. For example, the substrate may comprise a polymeric coating,also sometimes referred to herein as an “undercoating,” or a“precoating” over a metallic, ceramic, glass, polymeric, woven ornon-woven fiber or semi-metal core. Alternatively, the substrate maycomprise a polymeric material throughout, i.e., from its surface andinto its bulk. By way of further example, the substrate may comprise apolymeric coating, overlying a metallic, ceramic, glass, polymeric,woven or non-woven fiber or semi-metal core inner layer which, in turn,overlies a metallic, ceramic, glass, polymeric, woven or non-woven fiberor semi-metal core.

The substrate may be in the form of, or form part of, gels, liquids,films, particles (nanoparticles, microparticles, or millimeter diameterbeads), fibers (wound dressings, bandages, gauze, tape, pads, sponges,including woven and non-woven sponges and those designed specificallyfor dental or ophthalmic surgeries), blood storage bags, surgical,medical or dental instruments, blood oxygenators, stents (includingcoronary, ureteral, renal, biliary, colorectal, esophageal, pulmonary,urethral, vascular, peripheral, neurovascular), stent grafts (includingabdominal, thoracic, neurovascular and peripheral vascular), vena cavafilters, endovascular coils, catheters (including central venous,peripheral central, midline, peripheral, tunneled, dialysis access,urinary, neurological, peritoneal, intra-aortic balloon pump,angioplasty balloon, diagnostic, interventional, drug delivery, etc.),catheter connectors and valves (including needleless connectors),intravenous delivery lines and manifolds, drug delivery bags and tubing,implantable sensors (e.g., intravascular, transdermal, intracranial,glucose sensors), diagnostic devices (e.g., microfluidic,microelectromechanical, and optical), ophthalmic devices includingcontact lenses, intraocular lenses and phacoemulsification devices, orother medical devices used within or in contact with the body or anyportion of any of these.

In one particular embodiment, the substrate is an ophthalmic device;more preferably in this embodiment the substrate is a contact lens. Itis particularly useful to employ biocompatible materials hereinincluding both soft and rigid materials commonly used for ophthalmiclenses, including contact lenses. The preferred substrates are hydrogelmaterials, including silicone hydrogel materials. Particularly preferredmaterials include vinyl functionalized polydimethylsiloxanescopolymerized with hydrophilic monomers as well as fluorinatedmethacrylates and methacrylate functionalized fluorinated polyethyleneoxides copolymerized with hydrophilic monomers. Representative examplesof substrate materials for use herein include those disclosed in U.S.Pat. Nos. 5,310,779; 5,387,662; 5,449,729; 5,512,205; 5,610,252;5,616,757; 5,708,094; 5,710,302; 5,714,557 and 5,908,906, the contentsof which are incorporated by reference herein.

A wide variety of materials can be used herein, and silicone hydrogelcontact lens materials are particularly preferred. Hydrogels in generalare a well known class of materials that comprise hydrated, cross-linkedpolymeric systems containing water in an equilibrium state. Siliconehydrogels generally have a water content greater than about 5 weightpercent and more commonly between about 10 to about 80 weight percent.Such materials are usually prepared by polymerizing a mixture containingat least one silicone-containing monomer and at least one hydrophilicmonomer. Typically, either the silicone-containing monomer or thehydrophilic monomer functions as a crosslinking agent (a crosslinkerbeing defined as a monomer having multiple polymerizablefunctionalities) or a separate crosslinker may be employed. Applicablesilicone-containing monomeric units for use in the formation of siliconehydrogels are well known in the art and numerous examples are providedin U.S. Pat. Nos. 4,136,250; 4,153,641; 4,740,533; 5,034,461; 5,070,215;5,260,000; 5,310,779; 5,358,995; 5,760,100; 6,039,913; 7,919,136; and8,044,112; the contents of which are incorporated by reference herein.

Particular examples of bulky monomers are methacryloxypropyltris(trimethyl-siloxy)silane or tris(trimethylsiloxy)silylpropylmethacrylate, sometimes referred to as TRIS andtris(trimethylsiloxy)silylpropyl vinyl carbamate, sometimes referred toas TRIS-VC and the like. Such bulky monomers may be copolymerized with asilicone macromonomer, which is a poly(organosiloxane) capped with anunsaturated group at two or more ends of the molecule. U.S. Pat. No.4,153,641 discloses, for example, various unsaturated groups such asacryloxy or methacryloxy groups.

Another class of representative silicone-containing monomers includes,but is not limited to, silicone-containing vinyl carbonate or vinylcarbamate monomers such as, for example,1,3-bis[4-vinyloxycarbonyloxy)but-1-yl]tetramethyl-disiloxane;3-(trimethylsilyl)propyl vinyl carbonate;3-(vinyloxycarbonylthio)propyl-[tris(trimethylsiloxy)silane];3-[tris(trimethylsiloxy)silyl]propyl vinyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl allyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl vinyl carbonate;t-butyldimethylsiloxyethyl vinyl carbonate; trimethylsilylethyl vinylcarbonate; trimethylsilylmethyl vinyl carbonate and the like andmixtures thereof.

Another class of silicon-containing monomers includespolyurethane-polysiloxane macromonomers (also sometimes referred to asprepolymers), which may have hard-soft-hard blocks like traditionalurethane elastomers. They may be end-capped with a hydrophilic monomersuch as HEMA. Examples of such silicone urethanes are disclosed in avariety or publications, including Lai, Yu-Chin, “The Role of BulkyPolysiloxanylalkyl Methacryates in Polyurethane-Polysiloxane Hydrogels,”Journal of Applied Polymer Science, Vol. 60, 1193-1199 (1996). PCTPublished Application No. WO 96/31792 discloses examples of suchmonomers, which disclosure is hereby incorporated by reference in itsentirety.

Further examples of silicone-containing monomers include, withoutlimitation, methacryloxyalkylsiloxanes, 3-methacryloxypropylpentamethyldisiloxane,bis(methacryloxypropyl)tetramethyl-disiloxane, monomethacrylatedpolydimethylsiloxane, mercapto-terminated polydimethylsiloxane,N-[tris(trimethylsiloxy)silylpropyl]acrylamide,N-[tris(trimethylsiloxy)silylpropyl]methacrylamide, andtris(pentamethyldisiloxyanyl)-3-methacrylatopropylsilane (T2).

Any suitable siloxane-containing macromer with ethylenically unsaturatedgroup(s) can also be used to produce a silicone hydrogel material. Aparticularly preferred siloxane-containing macromer is selected from thegroup consisting of Macromer A, Macromer B, Macromer C, and Macromer Ddescribed in U.S. Pat. No. 5,760,100, herein incorporated by referencein its entirety. Macromers that contain two or more polymerizable groups(vinylic groups) can also serve as cross linkers. Di and triblockmacromers consisting of polydimethylsiloxane and polyakyleneoxides couldalso be of utility. Such macromers could be mono or difunctionalizedwith acrylate, methacrylate or vinyl groups. For example one might usemethacrylate end cappedpolyethyleneoxide-block-polydimethylsiloxane-block-polyethyleneoxide toenhance oxygen permeability.

Still other contact lens formulations are disclosed in U.S. Pat. No.5,710,302, WO 9421698, EP 406161, JP 2000016905, U.S. Pat. Nos.5,998,498, 6,087,415, 5,760,100, 5,776,999, 5,789,461, 5,849,811, and5,965,631, each of which is hereby incorporated by reference in theirentireties.

Still other contact lens formulations are disclosed in U.S. Pat. App.Pub. No. 2010/0048847 (e.g., “Filcon II 3”), which disclosure is herebyincorporated by reference in its entirety.

In one particular embodiment, the core polymeric bulk material of thecontact lens comprises a silicone elastomer, a silicone hydrogel, afluorohydrogel, a fluorosilicone hydrogel, poly-2-hydroxyethylmethacrylate (p-HEMA), or combinations thereof.

Representative examples of suitable bulk hydrophilic materials include,but are not limited to, the following materials known by the UnitedStates Approved Names of: abafilcon A, acofilcon A, acofilcon B,acquafilcon A, alofilcon A, alphafilcon A, amfilcon A, astifilcon A,atlafilcon A, balafilcon A, bisfilcon A, bufilcon A, comfilcon A,crofilcon A, cyclofilcon A, darfilcon A, delefilcon A, deltafilcon A,deltafilcon B, dimefilcon A, droxifilcon A, efrofilcon A, elastofilconA, enfilcon A, epsiflcon A, esterifilcon A, etafilcon A, focofilcon A,galyfilcon A, genfilcon A, govafilcon A, hefilcon A, hefilcon B,hefilcon C, hefilcon D, hilafilcon A, hilafilcon B, hioxifilcon A,hioxifilcon B, hioxifilcon C, hioxifilcon D, hydrofilcon A, iberfilconA, lenefilcon A, licryfilcon A, licryfilcon B, lidofilcon A, lidofilconB, lotrafilcon A, lotrafilcon B, mafilcon A, mesifilcon A, methafilconB, mipafilcon A, narafilcon A, narafilcon B, nelfilcon A, nesofilcon A,netrafilcon A, ocufilcon A, ocufilcon B, ocufilcon C, ocufilcon D,ocufilcon E, ocufilcon F, ofilcon A, omafilcon A, oxyfilcon A,pentafilcon A, perfilcon A, petrafocon A-hem-larafilcon A, pevafilcon A,phemfilcon A, phemfilcon B, polymacon A, polymacon B, senofilcon A,shofilcon A, sifilcon A, silafilcon A, siloxyfilcon A, surfilcon A,tasfilcon A, tefilcon A, tetrafilcon A, trifilcon A, uvifilcon A,vasurfilcon A, vifilcon A, vifilcon B, and xylofilcon A.

Representative examples of suitable bulk hydrophobic materials include,but are not limited to, the following materials known by the UnitedStates Approved Names of: amefocon A, amsilfocon A, aquilafocon A,arfocon A, cabufocon A, cabufocon B, carbosilfocon A, crilfocon A,crilfocon B, dimefocon A, enflufocon A, enflufocon B, erifocon A,filofocon A, fluorofocon A, flusilfocon A, flusilfocon B, flusilfocon C,flusilfocon D, flusilfocon E, hermafocon A, hexafocon A, hexafocon B,hirafocon A, hofocon A, hybufocon A, itabisfluorofocon A, itafluorofoconA, itafocon A, itafocon B, kolfocon A, kolfocon B, kolfocon C, kolfoconD, lotifocon A, lotifocon B, lotifocon C, melafocon A, migafocon A,nefocon A, nefocon B, nefocon C, onsifocon A, onsifocon B, oprifocon A,oxyflufocon A, paflufocon A, paflufocon B, paflufocon C, paflufocon D,paflufocon E, paflufocon F, paflufocon D-hem-iberfilcon A, pahrifocon A,pasifocon A, pasifocon B, pasifocon C, pasifocon D, pasifocon E,pemufocon A, petrafocon A-hem-larafilcon A, porofocon A, porofocon B,roflufocon A, roflufocon B, roflufocon C, roflufocon D, roflufocon E,rosilfocon A, satafocon A, siflufocon A, silafocon A, sterafocon A,sulfocon A, sulfocon B, telafocon A, tisilfocon A, tolofocon A, trifoconA, unifocon A, vinafocon A, and wilofocon A.

Where the medical device is a contact lens, for example, such lenses canbe manufactured employing various conventional techniques, to yield ashaped article having the desired posterior and anterior lens surfaces.Spincasting methods are disclosed in U.S. Pat. Nos. 3,408,429 and3,660,545 (herein incorporated by reference in their entireties); andstatic casting methods are disclosed in U.S. Pat. Nos. 4,113,224,4,197,266 and 5,271,876 (herein incorporated by reference in theirentireties). Curing of the monomeric mixture may be followed by amachining operation in order to provide a contact lens having a desiredfinal configuration. As an example, U.S. Pat. No. 4,555,732 (hereinincorporated by reference in its entirety) discloses a process in whichan excess of a monomeric mixture is cured by spincasting in a mold toform a shaped article having an anterior lens surface and a relativelylarge thickness. The posterior surface of the cured spincast article issubsequently lathe cut to provide a contact lens having the desiredthickness and posterior lens surface. Further machining operations mayfollow the lathe cutting of the lens surface, for example,edge-finishing operations.

For example, a mold (for cast molding) generally comprises at least twomold sections (or portions) or mold halves, i.e. first and second moldhalves. The first mold half defines a first molding (or optical) surfaceand the second mold half defines a second molding (or optical) surface.The first and second mold halves are configured to receive each othersuch that a lens forming cavity is formed between the first moldingsurface and the second molding surface. The molding surface of a moldhalf is the cavity-forming surface of the mold and in direct contactwith lens-forming material.

Methods of manufacturing mold sections for cast-molding a contact lensare generally well known to those of ordinary skill in the art. Theprocess of the present invention is not limited to any particular methodof forming a mold. In fact, any method of forming a mold can be used inthe present invention. The first and second mold halves can be formedthrough various techniques, such as injection molding or lathing.Examples of suitable processes for forming the mold halves are disclosedin U.S. Pat. No. 4,444,711; U.S. Pat. No. 4,460,534; U.S. Pat. No.5,843,346; and U.S. Pat. No. 5,894,002, which are also incorporatedherein by reference in their entireties.

Virtually all materials known in the art for making molds can be used tomake molds for making contact lenses. For example, polymeric materials,such as polyethylene, polypropylene, polystyrene, PMMA, Topas® COO grade8007-S10 (clear amorphous copolymer of ethylene and norbornene, fromTicona GmbH of Frankfurt, Germany and Summit, N.J.), or the like can beused. Other materials that allow UV light transmission could be used,such as quartz glass and sapphire.

Reusable molds may also be used and the silicone-hydrogel lens-formingmaterial can be cured actinically under a spatial limitation of actinicradiation to form a silicone hydrogel contact lens. Examples of reusablemolds are those disclosed in U.S. Pat. No. 6,627,124; U.S. Pat. No.6,800,225; and U.S. Pat. No. 7,384,590; which are incorporated herein byreference in their entireties.

In another embodiment, where a lens-forming material is a solution(e.g., dissolved in water, a mixture of water and a water miscibleorganic solvent, or an organic solvent), solvent-free liquid, or melt ofone or more silicone-containing prepolymers with ethylenicallyunsaturated groups optionally in presence of other components, reusablemolds are used and the lens-forming material is cured actinically undera spatial limitation of actinic radiation to form a colored contactlens. Examples of silicone-containing prepolymers include withoutlimitation those disclosed in U.S. Pat. No. 6,039,913; and U.S. Pat. No.7,091,283, which are incorporated herein by references in theirentireties.

In general, the lens-forming material is put into a mold consisting oftwo mold halves, the two mold halves not touching each other but havinga thin gap of annular design arranged between them. The gap is connectedto the mold cavity, so that excess lens material can flow away into thegap. Instead of polypropylene molds that can be used only once, it ispossible for reusable quartz, glass, sapphire molds to be used, since,following the production of a lens, these molds can be cleaned rapidlyand effectively off the uncrosslinked prepolymer and other residues,using water or a suitable solvent, and can be dried with air. Reusablemolds can also be made of Topas® COO grade 8007-S10 (clear amorphouscopolymer of ethylene and norbornene) from Ticona GmbH of Frankfurt,Germany and Summit, N.J. Because of the reusability of the mold halves,a relatively high outlay can be expended at the time of their productionin order to obtain molds of extremely high precision andreproducibility. Since the mold halves do not touch each other in theregion of the lens to be produced, i.e., the cavity or actual moldfaces, damage as a result of contact is ruled out. This ensures a highservice life of the molds, which, in particular, also ensures highreproducibility of the contact lenses to be produced.

The two opposite surfaces (anterior surface and posterior surface) of acontact lens are defined by the two molding surfaces while the edge isdefined by the spatial limitation of actinic irradiation rather than bymeans of mold walls. Typically, only the lens-forming material within aregion bound by the two molding surfaces and the projection of the welldefined peripheral boundary of the spatial limitation is crosslinkedwhereas any lens-forming material outside of and immediately around theperipheral boundary of the spatial limitation is not crosslinked, andthereby the edge of the contact lens should be smooth and preciseduplication of the dimension and geometry of the spatial limitation ofactinic radiation. Such methods of making contact lenses are describedin U.S. Pat. No. 6,627,124; U.S. Pat. No. 6,800,225; and U.S. Pat. No.7,384,590; which are incorporated by reference in their entireties.

A spatial limitation of actinic radiation (or the spatial restriction ofenergy impingement) can be effected by masking for a mold that is atleast partially impermeable to the particular form of energy used, asillustrated in U.S. Pat. No. 6,627,124; and U.S. Pat. No. 6,800,225(herein incorporated by reference in their entireties) or by a mold thatis highly permeable, at least at one side, to the energy form causingthe crosslinking and that has mold parts being impermeable or of poorpermeability to the energy, as illustrated in U.S. Pat. No. 6,627,124;U.S. Pat. No. 6,800,225; and U.S. Pat. No. 7,384,590; (hereinincorporated by reference in their entireties). The energy used for thecrosslinking is radiation energy, especially UV radiation, gammaradiation, electron radiation or thermal radiation, the radiation energypreferably being in the form of a substantially parallel beam in orderon the one hand to achieve good restriction and on the other handefficient use of the energy.

Surface Modifications

In general, a non-fouling polymeric material is grafted from a medicaldevice substrate, such as a contact lens. Various processes and processsteps can be employed in applying the surface modification. Theparticular process(es) and process step(s) chosen may depend, at leastin part, upon the substrates being modified, the polymeric materialsbeing applied and their monomeric precursors, the polymerizationtechnique(s), and/or the desired properties of the modified surface. Insome embodiments, for example, a redox initiator is used to graft fromfunctional groups contained within the lens material, such as graftingfrom hydroxyl groups in the presence of Ce(IV). In some embodiments, forexample, a UV initiator present in the lens that is residual from thelens molding process is used to graft a non-fouling polymeric material.In some embodiments, for example, a UV initiator is added to the contactlens during the lens molding process that is, in turn, used to graft anon-fouling polymeric material. In some embodiments, for example, anon-fouling polymeric material is grafted from a contact lens substrateinto which one or more polymerization initiators have been incorporated.In some embodiments, for example, the non-fouling polymeric material isgrafted from a substrate that is a composite of two or more materials.Combinations of these and other processes and process steps may also beemployed.

Preferably, the non-fouling polymeric material that is grafted from thesubstrate comprises a chain-growth polymer (that is, a polymer orpolymer block formed by addition polymerization), or a combinationthereof. The chain-growth polymer may be, for example, an additionpolymer derived from monomer(s) incorporating double or triple bonds,e.g., an olefin. By way of further example, the chain-growth polymer maycomprise an addition polymer derived from a cyclic monomer by means of aring-opening polymerization reaction. Thus, the polymer may be achain-growth homopolymer or copolymer. In a preferred embodiment, thepolymer is a chain growth addition homopolymer or a chain growthaddition copolymer comprising the residue of two or more monomers.

In accordance with one aspect of the present invention, it is generallypreferred that the non-fouling polymeric material be prepared withoutinordinate use of a polyfunctional crosslinking agent. For example, itis generally preferred that the non-fouling polymeric material containless than 50 mole % of the residue of a polyvalent crosslinker. In onesuch embodiment, the non-fouling polymeric material contains less than25 mole % of the residue of a polyvalent crosslinker. In one suchembodiment, non-fouling polymeric material contain less than 10 mole %of a polyvalent crosslinker. In one such embodiment, the non-foulingpolymeric material contains less than 5 mole % of the residue of apolyvalent crosslinker. In one such embodiment, non-fouling polymericmaterial contain less than 3 mole % of a polyvalent crosslinker. In onesuch embodiment, the non-fouling polymeric material contains less than0.1 mole % of the residue of a polyvalent crosslinker. In one suchembodiment, the non-fouling polymeric material contains no residue of apolyvalent crosslinker.

Through grafting, step-growth or chain-growth techniques, thenon-fouling polymeric material may comprise any of a range of polymertypes or combinations thereof. The polymer backbone may be neutral(e.g., polyalkylene or polyether) or contain permanently chargedmoieties (e.g., cyclic or acyclic quaternized nitrogen atoms), or evenzwitterionic backbones (e.g., phosphorylcholine backbones). In oneembodiment, therefore, the non-fouling polymeric material comprises apolymer or copolymer selected from the group consisting of polyamide,polyamine, polyanhydride, polyazine, poly(carbonate), polyester,polyether, polyetheretherketone (PEEK), polyguanidine, polyimide,polyketal, poly(ketone), polyolefin, poly(orthoester), polyphosphazine,polysaccharide, polysiloxane, polysulfone, polyurea, polyurethane,halogenated polymer, silicone, hydrocarbon, ether-ester, ether-amide orionized polyethylene and combinations thereof.

The polymer may also contain a wide range of pendant (side-chain)groups, hydrophilic and hydrophobic, neutral, anionic, cationic, ormixed charged. For example, the pendant groups may include neutralhydrophilic groups such as hydroxy, oligo(ethylene glycol) and/orpoly(ethylene glycol) moieties, or it may include charged groups such asanionic moieties, cationic moieties, and zwitterionic moieties.

Zwitterionic Groups

Zwitterions are molecules that carry formal positive and negativecharges on non-adjacent atoms within the same molecule and moleculesthat may be ionized by addition or removal of an electrophile or anucleophile, or by removal of a protecting group. Both natural andsynthetic polymers, containing zwitterion functionality, have been shownto resist protein adhesion. In one embodiment, the zwitterionic monomercontains a phosphorylcholine moiety, a carboxyammonium moiety, asulfoammonium moiety, derivatives thereof, or combinations thereof. Inone embodiment, the zwitterionic monomer contains a carboxyammoniummoiety, a sulfoammonium moiety, derivatives thereof, or combinationsthereof. In one embodiment, the zwitterionic monomer contains asulfobetaine moiety or a carboxybetaine moiety. The zwitterionic polymermay be formed by initiating polymerization with radicals present in thepolymeric substrate, in the presence of one or more monomers, such assulfobetaine methacrylate or carboxybetaine methacrylate monomers.

Polysulfoammonium polymers such as polysulfobetaines,polycarboxyammonium polymers such as polycarboxybetaines and othernatural and synthetic zwitterion chemistries can be used to designnon-fouling materials for the biomedical applications described herein.Some examples of natural zwitterions chemistries that could be used fornon-fouling materials include, but are not limited to, amino acids,peptides, natural small molecules including, but not limited to,N,N,N-trimethylglycine (glycine betaine), trimethylamine oxide (TMAO),dimethylsulfoniopropionate sarcosine, lysergic acid and psilocybin.Additional synthetic zwitterions that could be used to createnon-fouling materials, include, but are not limited to, amino-carboxylicacids (carboxybetaines), amino-sulfonic acids (sulfo betaines),cocamidopropyl betaine, quinonoid based zwitterions,decaphenylferrocene, and non-natural amino acids. Natural and syntheticpolymers also include mixed charged structures with both positivecharged and negative charged moieties on the pendant groups, in the mainchains, or at the terminal groups.

Materials containing, or composed of, these natural or syntheticzwitterions, can be grafted from surfaces, particularly the surfaces ofmedical devices, in order to improve biocompatibility, reducethrombogenesis (such as on the surface of stents or venous valves), andreduce fouling by proteins or bacteria present in solution. This isparticularly applicable for surfaces where non-specific binding ofproteins in solution could negatively impact the desired or necessarymechanics of a device.

In one embodiment, the non-fouling polymer contains zwitterionic pendantgroups covalently attached, directly or indirectly to the polymer backbone. The zwitterionic pendant groups may have an overall net charge,for instance, by having a divalent center of anionic charge andmonovalent center of cationic charge or vice versa, or by having twocenters of cationic charge and one center of anionic charge or viceversa. Preferably, however, the zwitterion has no overall net charge andmost preferably has a center of monovalent cationic charge and a centerof monovalent anionic charge. Additionally, the center(s) of cationiccharge are preferably permanent; that is, it is preferably a quaternarynitrogen, quaternary phosphonium or tertiary sulfonium group.Additionally, the center(s) of anionic charge are also permanent; thatis, they are completely ionized at physiological pH and are preferablycarboxylate, phosphate, phosphonic, phosphonate, sulfate, sulfinic, orsulfonate.

In another embodiment, the polymer contains zwitterionic pendant groupscovalently attached, directly or indirectly, to the polymer back bone,and the zwitterion corresponds to Formula ZI-3:

wherein

T⁸ is a bond, hydrocarbylene, substituted hydrocarbylene, heterocyclo,or in combination with T⁹ and T¹⁰ and the nitrogen atom to which theyare attached form a nitrogen-containing heteroaromatic ring,

T⁹ and T¹⁰ are independently hydrogen, hydrocarbyl, substitutedhydrocarbyl or heterocyclo, or, T⁹ and T¹⁰, in combination with T⁸ andthe nitrogen atom to which they are attached form a nitrogen-containingheteroaromatic ring,

T¹¹ is hydrocarbylene, substituted hydrocarbylene, ether, or oxylatedalkylene,

Z³ is carboxylate, phosphate, phosphonic, phosphonate, sulfate,sulfinic, or sulfonate, and

* designates the point of covalent attachment, direct or indirect, ofthe zwitterion of Formula ZI-3 to the polymer backbone.

In certain preferred embodiments in which the polymer containszwitterionic pendant group corresponding to Formula ZI-3, T⁸, T⁹, T¹⁰,and T¹¹ are selected from a more narrow range of substituents, Z³ iscarboxylate or sulfate, and the zwitterion corresponds to Formula ZI-4:

wherein * designates the point of covalent attachment, direct orindirect, of the zwitterion of Formula ZI-4 to the polymer backbone; T¹²is a bond or —(CH₂)_(m)— with m being 1 to 3; T¹³ and T¹⁴ areindependently hydrogen, alkyl, or substituted alkyl; T¹⁵ is optionallysubstituted alkylene, phenylene, ether, or oxylated alkylene; and Z⁴ iscarboxylate or sulfate. For example, in this embodiment, T¹³ and T¹⁴ mayindependently be hydrogen or lower alkyl, e.g., methyl, ethyl, orpropyl. By way of further example, in this embodiment, T¹³ and T¹⁴ mayindependently be hydrogen or lower alkyl, e.g., methyl, ethyl, orpropyl. By way of further example, in this embodiment, T¹⁵ may be—(CH₂)_(n)— with n being 1-8. By way of further example, in thisembodiment, T¹⁵ may be —(CH₂)₂— or —(CH₂)₃— and T¹³ and T¹⁴ may bemethyl. By way of further example, in this embodiment, T¹⁵ may be—(CH₂)₂— or —(CH₂)₃—, T¹³ and T¹⁴ may be hydrogen or alkyl. By way offurther example, in this embodiment, T¹² may be —(CH₂)₂—, T¹³ and T¹⁴may be methyl, T¹⁵ may be —(CH₂)₂— and Z⁴ may be carboxylate. By way offurther example, in this embodiment, T¹² may be —(CH₂)₂—, T¹³ and T¹⁴may be methyl, T¹⁵ may be —(CH₂)₃— and Z⁴ may be sulfate.

In certain preferred embodiments in which the polymer containszwitterionic pendant group corresponding to Formula ZI-3, T⁸, T⁹ and T¹⁰and the nitrogen atom to which they are attached form anitrogen-containing heteroaromatic ring. For example, T⁸, T⁹ and T¹⁰ andthe nitrogen atom to which they are attached may form an optionallysubstituted heterocycle, containing a quaternary nitrogen atom. One suchembodiment corresponds to Formula ZI-5:

wherein * designates the point of covalent attachment, direct orindirect, of the zwitterion of Formula ZI-5 to the polymer backbone; HETis a heterocycle containing a quaternary nitrogen atom, T¹⁵ isoptionally substituted alkylene, phenylene, ether, or oxylated alkylene;and Z⁴ is carboxylate or sulfate. For example, in this embodiment, T¹⁵may be —(CH₂)_(n)— with n being 1-8. By way of further example, in thisembodiment, T¹⁵ may be —(CH₂)₂— or —(CH₂)₃— and Z⁴ may be carboxylate orsulfate. By way of further example, in this embodiment, T¹⁵ may be—(CH₂)₃— and Z⁴ may be sulfate. By way of further example, in thisembodiment, T¹⁵ may be —(CH₂)₂— and Z⁴ may be carboxylate. Exemplaryzwitterions corresponding to Formula ZI-5 include zwitterionscorresponding to Formulae ZI-6A and ZI-6B:

wherein * designates the point of covalent attachment, direct orindirect, of the zwitterion of Formulae ZI-6A and ZI-6B to the polymerbackbone; T¹⁵ is optionally substituted alkylene, phenylene, ether, oroxylated alkylene; and Z⁴ is carboxylate or sulfate. For example, inthis embodiment, T¹⁵ may be —(CH₂)_(n)— with n being 1-8. By way offurther example, in this embodiment, T¹⁵ may be —(CH₂)₂— or —(CH₂)₃— andZ⁴ may be carboxylate or sulfate. By way of further example, in thisembodiment, T¹⁵ may be —(CH₂)₃— and Z⁴ may be sulfate. By way of furtherexample, in this embodiment, T¹⁵ may be —(CH₂)₂— and Z⁴ may becarboxylate.

In one embodiment, the polymer contains zwitterionic pendant groupscovalently attached, directly or indirectly, to the polymer back bone,and the zwitterion corresponds to Formula ZI-7

wherein T⁴, T⁵ and T⁶ are independently hydrogen, hydrocarbyl,substituted hydrocarbyl or heterocyclo; T¹² is a bond, hydrocarbylene,substituted hydrocarbylene, or heterocyclo, and * designates the pointof covalent attachment, direct or indirect, of the zwitterion of FormulaZI-7 to the polymer backbone.

In one embodiment, the polymer contains zwitterionic pendant groupscovalently attached, directly or indirectly, to the polymer back bone,and the zwitterion corresponds to Formula ZI-1:

wherein

T¹ and T² are independently oxygen, sulfur, NH or a bond,

T³ is hydrocarbylene, substituted hydrocarbylene, ether, or oxylatedalkylene,

Z¹ is a moiety comprising a quaternary nitrogen, phosphonium orsulfonium cationic group, and

* designates the point of covalent attachment, direct or indirect, ofthe zwitterion of Formula ZI-1 to the polymer backbone.

In certain preferred embodiments in which the polymer containszwitterionic pendant group corresponding to Formula ZI-1, T¹ and T² areoxygen, Z¹ is quaternary nitrogen, and the zwitterion corresponds toFormula ZI-2:

wherein * designates the point of covalent attachment of the zwitterionof Formula ZI-2 to the polymer backbone, T³ is hydrocarbylene,substituted hydrocarbylene, or oxylated alkylene, and T⁴, T⁵ and T⁶ areindependently hydrogen, hydrocarbyl, substituted hydrocarbyl orheterocyclo. For example, in this embodiment, T³ may be —(CH₂)_(n)— withn being 1-8. By way of further example, in this embodiment, T⁴, T⁵ andT⁶ may independently be lower alkyl, e.g., methyl, ethyl or propyl. Byway of further example, in this embodiment, T³ may be —(CH₂)_(n)— with nbeing 1-3, and T⁴, T⁵ and T⁶ may independently be lower alkyl, e.g.,methyl, ethyl or propyl. By way of further example, in this embodiment,T³ may be —(CH₂)_(n)— with n being 1-3, and one or more of T⁴, T⁵ and T⁶may be substituted hydrocarbyl such as oligomeric phosphorylcholine(e.g., Formula 9).

Neutral Hydrophilic Pendant Groups

In one embodiment, the polymer contains neutral hydrophilic pendantgroups covalently attached, directly or indirectly, to the polymerbackbone. Exemplary neutral hydrophilic groups include hydroxy, thiol,oxylated alkyls (e.g., oligoethylene glycol, polyethylene glycol and/orpolypropylene glycol), ether, thioether, and the like. In one suchspecific embodiment, the polymer contains pendant groups comprisingalkoxylated moieties corresponding to Formula POA-1:

wherein a is 1-3, b is 1-8, each R¹ and R² is independently selectedfrom the group consisting of hydrogen, halogen, and optionallysubstituted lower alkyl, R³ is hydrocarbyl, substituted hydrocarbyl orheterocyclo, and * designates the point of attachment of the moietiescorresponding to Formula POA-1 to the remainder of the pendant group andthe backbone. By way of example, in one such embodiment, each R¹ and R²are hydrogen, n is 2 or 3. By way of further example, in one suchembodiment, each R¹ and R² is hydrogen, n is 2 or 3, and b is 3-5. Byway of further example, in one such embodiment, each R¹ and R² ishydrogen, n is 2 or 3, b is 3-5, and R³ is alkyl. In one embodiment, therepeat units are derived from macromonomers containing 2-20 alkyleneoxide units.

Repeat Units

In general, homopolymers or copolymers comprising zwitterionic pendantgroups, neutral hydrophilic pendant groups, cationic pendant groupsand/or anionic pendant groups may be prepared by polymerization of anyof a wide range of monomers. In one preferred embodiment, thenon-fouling polymeric material is a homopolymer or copolymer comprisingrepeat units derived from an olefinic monomer. Thus, for example, in oneembodiment the non-fouling polymeric material comprises repeat unitsderived from an olefinic monomer and corresponding to Formula 1:

wherein

X¹ and X² are independently hydrogen, hydrocarbyl, substitutedhydrocarbyl, heterocyclo, or substituted carbonyl, provided, however, X¹and X² are not each selected from the group consisting of aryl,heteroaryl, and heterosubstituted carbonyl,

X³ is hydrogen, alkyl or substituted alkyl,

X⁴ is —OX⁴⁰, —NX⁴¹X⁴², —N⁺X⁴¹X⁴²X⁴³, —SX⁴⁰, aryl, heteroaryl or acyl,

X⁴⁰ is hydrogen, hydrocarbyl, substituted hydrocarbyl, heterocyclo oracyl, and

X⁴¹, X⁴² and X⁴³ are independently hydrogen, hydrocarbyl, substitutedhydrocarbyl or heterocyclo.

In certain embodiments in which the non-fouling polymeric materialcomprises repeat units corresponding to Formula 1, it is preferred thatX⁴ of at least a fraction of the repeat units comprise alkoxylatedmoieties, zwitterionic moieties, anionic moieties, or cationic moieties.In such embodiments, for example, X¹ and X² may be hydrogen, and thepolymer comprises repeat units corresponding to Formula 2:

wherein X³ is hydrogen, alkyl or substituted alkyl, and X⁴ is a pendantgroup comprising an oxylated alkylene moiety, a zwitterionic moiety, ananionic moiety, or a cationic moiety. For example, X³ may be hydrogen orlower alkyl. By way of further example, X⁴ may be a pendant groupcomprising an oxylated alkylene moiety corresponding to Formula POA-1.By way of further example, the repeat unit of Formula 2 may bezwitterionic repeat unit comprising a zwitterionic moiety correspondingto Formula ZI-1, ZI-2, ZI-3, ZI-4, ZI-5, ZI-6A, ZI-6B, or ZI-7. By wayof further example, the repeat unit of Formula 2 may be a cationicrepeat unit. By way of further example, the repeat unit of Formula 2 maybe an anionic repeat unit. By way of further example, X³ may be hydrogenor methyl and X⁴ may be a pendant group comprising an oxylated alkylenemoiety corresponding to Formula POA-1 or a zwitterionic moietycorresponding to Formula ZI-1, ZI-2, ZI-3, ZI-4, ZI-5, ZI-6A, ZI-6B, orZI-7.

In one presently preferred embodiment, the non-fouling polymericmaterial comprises repeat units corresponding to Formula 2 wherein X⁴ isacyl and the repeat units correspond to Formula 3:

wherein X⁴⁴ comprises an oxylated alkylene moiety, a zwitterionicmoiety, an anionic moiety, or a cationic moiety. For example, X⁴⁴ may be—OX⁴⁵, —NX⁴⁵X⁴⁶ or —SX^(45′), wherein X⁴⁵ is a substituted hydrocarbylor heterocyclo moiety comprising an oxylated alkylene moiety, azwitterionic moiety, an anionic moiety, or a cationic moiety, and X⁴⁶ ishydrogen, hydrocarbyl, substituted hydrocarbyl or heterocyclo. Forexample, X³ may be hydrogen or lower alkyl. By way of further example,X⁴⁴ may be —OX⁴⁵, or —NHX⁴⁵. By way of further example, X⁴⁴ may be—OX⁴⁵, or —NHX⁴⁵ wherein X⁴⁵ comprises an oxylated alkylene moietycorresponding to Formula POA-1. By way of further example, X⁴⁴ may be—OX⁴⁵, or —NHX⁴⁵ wherein X⁴⁵ comprises a zwitterionic moietycorresponding to Formula Z1-1, ZI-2, ZI-3, ZI-4, ZI-5, ZI-6A, ZI-6B, orZI-7. By way of further example, the repeat unit of Formula 3 may be acationic repeat unit. By way of further example, the repeat unit ofFormula 3 may be an anionic repeat unit. By way of further example, X³may be hydrogen or methyl and X⁴⁴ may comprise an oxylated alkylenemoiety corresponding to Formula POA-1 or a zwitterionic moietycorresponding to Formula ZI-1, ZI-2, ZI-3, ZI-4, ZI-5, ZI-6A, ZI-6B, orZI-7. In one particularly preferred embodiment, the polymer containsrepeat units corresponding to Formula 3 and X⁴⁴ is—O(CH₂)₂N⁺(CH₃)₂(CH₂)_(n)SO₃ ⁻, —O(CH₂)₂N⁺(CH₃)₂(CH₂)_(n)CO₂,—NH(CH₂)₃N⁺(CH₃)₂(CH₂)_(n)CO₂, or —NH(CH₂)₃N⁺(CH₃)₂(CH₂)_(n)SO₃, whereinn is 1-8. In one embodiment, the polymer contains repeat unitscorresponding to Formula 3 and X⁴⁴ is—NH(CH₂)_(m)N(CH₂)_(n)CH₃(CH₂)_(p)SO₃, —NH(CH₂),N(CH₂)_(n)CH₃(CH₂)_(p)CO₂, —NH(CH₂)_(m)N⁺[(CH₂)_(n)CH₃]₂(CH₂)_(p)SO₃,—NH(CH₂)N⁺[(CH₂)_(n)CH₃]₂ (CH₂)_(p)CO₂, —NH(CH₂)_(m)Ncyclo-(CH₂)_(p)CO₂,or —NH(CH₂)_(m)Ncyclo-(CH₂)_(p)SO₃, (Ncyclo is a heterocyclic structureor a heterocyclic derivative containing at least one nitrogen element),wherein m is 1-8; n is 0-5; and p is 1-8. In one embodiment, the polymercontains repeat units corresponding to Formula 3 and X⁴⁴ is—O(CH₂)_(m)N(CH₂)_(n)CH₃(CH₂)_(p)SO₃,—O(CH₂)_(m)N(CH₂)_(n)CH₃(CH₂)_(p)CO₂,—O(CH₂)_(m)N⁺[(CH₂)_(n)CH₃]₂(CH₂)_(p)SO₃, —O(CH₂)N⁺[(CH₂)_(n)CH₃]₂(CH₂)_(p)CO₂, —O(CH₂)_(m)Ncyclo-(CH₂)_(p)CO₂, or-0(CH₂)_(m)Ncyclo-(CH₂)_(p)SO₃ wherein m is 1-8; n is 0-5; and p is 1-8.In one embodiment, the polymer contains repeat units corresponding toFormula 3 and X⁴⁴ is —O(CH₂)₂N⁺(CH₃)₂(CH₂)₃SO₃,—O(CH₂)₂N⁺(CH₂)₂(CH₃)₂(CH₂)₂CO₂, —NH(CH₂)₂N⁺(CH₃)₂(CH₂)₃SO₃,—NH(CH₂)₂N⁺(CH₃)₂(CH₂)₂CO₂, —NH(CH₂)₃N⁺(CH₃)₂(CH₂)₃SO₃,—NH(CH₂)₃N⁺(CH₃)₂(CH₂)₂CO₂, —O(CH₂)₂)₂N⁺(CH₂CH₃)₂(CH₂)₃SO₃,—O(CH₂)₂N⁺(CH₂CH₃)₂(CH₂)₂CO₂, —O(CH₂)₂N⁺(CH₂CH₂CH₂CH₃)₂ (CH₂)₃SO₃,—O(CH₂)₂N⁺(CH₂CH₂CH₂CH₃)₂(CH₂)₂CO₂ or —NH(CH₂)₃Ncyclo-(CH₂)₃SO₃.

In one preferred embodiment, the non-fouling polymeric material is azwitterionic polymer or copolymer. For example, the non-foulingpolymeric material may comprise carboxybetaine repeat units and/orsulfobetaine repeat units. Alternatively, the non-fouling polymericmaterial may be a polyampholyte, containing anionic and cationic repeatunits. Optionally, the non-fouling polymer may contain poly(ethyleneoxide) repeat units and/or other neutral olefinic repeat units. Thus,for example, in one preferred embodiment, the non-fouling polymericmaterial is a zwitterionic polymer or copolymer comprising the repeatunits of Formula 4:

a is 0-1; b is 0-1; c is 0-1; d is 0-1; m is 1-20; n and o areindependently 0-11; p and q are independently 0-11; X³ is hydrogen,alkyl or substituted alkyl, X⁴ is —OX⁴⁰, —NX⁴¹X⁴², —SX⁴⁰, aryl,heteroaryl or acyl; X⁴⁰ is hydrogen, hydrocarbyl, substitutedhydrocarbyl, heterocyclo or acyl; X⁴¹ and X⁴² are independentlyhydrogen, hydrocarbyl, substituted hydrocarbyl or heterocyclo; and X⁴⁹is hydrogen, hydrocarbyl or substituted hydrocarbyl, provided the sum ofa, b, c and d is greater than 0 and X⁴ of repeat unit D differs from thecorresponding pendant group of repeat units A, B and C. In one suchembodiment, X³ is hydroxy-substituted alkyl such as hydroxypropyl.

In certain embodiments, the non-fouling polymeric material is ahomopolymer or copolymer comprising repeat units corresponding toFormula 5, Formula 6, Formula 7, Formula 8, or Formula 9:

HET is part of a heterocyclic structure,

X³ is hydrogen, alkyl or substituted alkyl,

X⁴ is —OX⁴⁰, —NX⁴¹X⁴², —SX⁴⁰, aryl, heteroaryl or acyl,

X⁵ is ester, anhydride, imide, amide, ether, thioether, thioester,hydrocarbylene, substituted hydrocarbylene, heterocyclo, urethane, orurea;

X⁶ is hydrocarbylene, substituted hydrocarbylene, heterocyclo, amide,anhydride, ester, imide, thioester, thioether, urethane, or urea;

X⁷ is hydrogen, alkyl or substituted alkyl;

X⁸ is an anionic moiety;

X⁹ is hydrocarbylene, substituted hydrocarbylene, heterocyclo, amide,anhydride, ester, imide, thioester, thioether, urethane, or urea;

X¹⁰ is hydrogen, alkyl or substituted alkyl;

X¹¹ is a cationic moiety;

X¹² is hydrocarbylene, substituted hydrocarbylene, heterocyclo, amide,anhydride, ester, imide, thioester, thioether, urethane, or urea;

X¹³ is hydrogen, alkyl or substituted alkyl;

X¹⁴ is an anionic moiety;

L¹ and L² are independently hydrocarbylene, substituted hydrocarbylene,heterocyclo, amide, anhydride, ester, imide, thioester, thioether,urethane, or urea; and

X⁴⁰ is hydrogen, hydrocarbyl, substituted hydrocarbyl, heterocyclo oracyl, and

X⁴¹ and X⁴² are independently hydrogen, hydrocarbyl, substitutedhydrocarbyl or heterocyclo.

In one embodiment, the non-fouling polymeric material comprises repeatunits corresponding to Formula 7 wherein the heterocycle, HETcorresponds to Formulae 10, 11 or 12:

wherein X⁶ is hydrocarbylene, substituted hydrocarbylene, heterocyclo,amide, anhydride, ester, imide, thioester, thioether, urethane, or urea;X⁷ is hydrogen, alkyl or substituted alkyl; and X⁸ is an anionic moiety.

Suitable comonomers include, but are not limited to, acrylates,acrylamides, vinyl compounds, multifunctional molecules, such as di-,tri-, and tetraisocyanates, di-, tri-, and tetraols, di-, tri-, andtetraamines, and di-, tri-, and tetrathiocyanates; cyclic monomers, suchas lactones and lactams, and combination thereof. In the interests ofbrevity, exemplary methacrylate monomers are listed below (but it shouldbe understood that analogous acrylate, acrylamide and methacrylamidemonomers may be similarly listed and are similarly included):

Charged methacrylates or methacrylates with primary, secondary ortertiary amine groups, such as, 3-sulfopropyl methacrylate potassiumsalt, (2-dimethylamino)ethyl methacrylate) methyl chloride quaternarysalt, [2-(methacryloyloxy)ethyl]trimethyl-ammonium chloride,methacryloyl chloride, [3-(methacryloylamino)propyl]-trimethylammoniumchloride), 2-aminoethyl methacrylate hydrochloride,2-(diethylamino)ethyl methacrylate, 2-(dimethylamino)ethyl methacrylate,2-(tert-butylamino)ethyl methacrylate, and 2-(tert-butylamino-ethylmethacrylate.

Alkyl methacrylates or other hydrophobic methacrylates, such as ethylmethacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexylmethacrylate, methyl methacrylate, lauryl methacrylate, isobutylmethacrylate, isodecyl methacrylate, phenyl methacrylate, decylmethacrylate, 3,3,5-trimethylcyclohexyl methacrylate, benzylmethacrylate, cyclohexyl methacrylate, stearyl methacrylate, tert-butylmethacrylate, tridecyl methacrylate, 2-naphthyl methacrylate,2,2,3,3-tetrafluoropropyl methacrylate, 1,1,1,3,3,3-hexafluoroisopropylmethacrylate, 2,2,2-trifluoroethyl methacrylate,2,2,3,3,3-pentafluoropropyl methacrylate, 2,2,3,4,4,4-hexafluorobutylmethacrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate,2,2,3,3,4,4,5,5-octafluoropentyl methacrylate,3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl methacrylate, and3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate.

Reactive or crosslinkable methacrylates, such as2-(trimethylsilyloxy)ethyl methacrylate, 3-(trichlorosilyl)propylmethacrylate, 3-(trimethoxysilyl)propyl methacrylate,3-[tris(trimethylsiloxy)silyl]propyl methacrylate, trimethylsilylmethacrylate, allyl methacrylate, vinyl methacrylate,3-(acryloyloxy)-2-hydroxypropyl methacrylate,3-(diethoxymethylsilyl)propyl methacrylate 3-(dimethylchlorosilyl)propylmethacrylate 2-isocyanatoethyl methacrylate, glycidyl methacrylate,2-hydroxyethyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate,Hydroxybutyl methacrylate, glycol methacrylate, hydroxypropylmethacrylate, and 2-hydroxypropyl 2-(methacryloyloxy)ethyl phthalate.

Other methacrylates, such as ethylene glycol methyl ether methacrylate,di(ethylene glycol) methyl ether methacrylate, ethylene glycol phenylether methacrylate, 2-butoxyethyl methacrylate, 2-ethoxyethylmethacrylate, and ethylene glycol dicyclopentenyl ether methacrylate.

Multifunctional monomers, such as di, tri, or tetraacrylates and di,tri, or tetraacrylamides can be used to form highly branched structureswhich can provide a higher concentration of non-fouling groups on thesurface. As previously noted, the non-fouling polymeric material maycontain a non-zwitterionic non-fouling material, alone or in combinationwith a zwitterionic material. These non-fouling groups may have varyingdegrees of non-fouling performance in a range of environments. Suitablenon-zwitterionic materials include, but are not limited to, polyethers,such as polyethylene glycol, poly(ethylene oxide-co-propylene oxide)(PEO-PPO) block copolymers, polysaccharides such as dextran, hydrophilicpolymers such as polyvinylpyrrolidone (PVP) andhydroxyethyl-methacrylate (HEMA), acrylonitrile-acrylamide copolymers,heparin, heparin fragments, derivatized heparin fragments, hyaluronicacid, mixed charge materials, and materials containing hydrogen bondaccepting groups, such as those described in U.S. Pat. No. 7,276,286(herein incorporated by reference in its entirety). Suitable polymerstructures included, but are not limited to, polymers or copolymerscontaining monomers of Formula I wherein ZI is replaced by anon-zwitterionic, non-fouling head group.

In one embodiment, the non-fouling material is a polymer containingrepeat units derived from sulfobetaine-containing and/orcarboxybetaine-containing monomers. Examples of monomers includesulfobetaine methacrylate (SBMA), sulfobetaine acrylamide, sulfobetainemethacrylamide, carboxybetaine methacrylate (CBMA), carboxybetaineacrylamide and carboxybetaine methacrylamide. Examples of such polymersinclude, but are not limited to, poly(carboxy betaine methacrylate)(polyCBMA), poly(carboxybetaine acrylamide), poly(carboxybetainemethacrylamide) poly(sulfobetaine methacrylate) (polySBMA),poly(sulfobetaine acrylamide), and poly(sulfobetaine methacrylamide). Inanother embodiment, the non-fouling material polymer is a polymercontaining the residue of CBMA or SBMA and one or more additionalmonomers. The additional monomers can be zwitterionic ornon-zwitterionic monomers.

In some embodiments, it is preferred to have use zwitterionic polymersthat possess permanently charged groups, which, without being bound byany theory, may improve non-fouling performance because the chargedgroups are ionically solvated with water. The presence of commonly usedgroups which can have permanent charges in the zwitterionic polymers canbe detected by using XPS to analyze the elements present in the topapproximately 1-50 nm of the surface. One representative group commonlyused in zwitterions is nitrogen in quaternary amine groups. Insulfobetaine, elemental signal of nitrogen may be approximatelyequivalent to a signal for sulfur. Further, techniques such as TOF-SIMSmay be used to identify zwitterionic groups in the grafted polymerlayer. In some preferred embodiments, the grafted polymer layer containsXPS signals of nitrogen, and optionally sulfur.

In general, the grafted polymeric material may comprise repeat unitscorresponding to any of Formulae 1 to 12. By way of further example, thegrafted polymeric material may comprise a zwitterionic polymer. By wayof further example, polymeric material may comprise repeat unitscorresponding to Formula 1. By way of further example, the graftedpolymeric material may comprise repeat units corresponding to Formula 2.By way of further example, the grafted polymeric material may compriserepeat units corresponding to Formula 3. By way of further example, thegrafted polymeric material may comprise repeat units corresponding toFormula 4. Additionally, the grafted polymeric material may comprise, aspendant groups, any of the pendant groups disclosed herein. Thus, forexample, the grafted polymeric material may comprise pendant groupscorresponding to any of Formulae ZI-1 to ZI-7 or POA-1. In oneparticularly preferred embodiment, the grafted polymeric materialcorresponds to Formula 1 and comprises zwitterionic pendant groups. Inanother particularly preferred embodiment, the grafted polymericmaterial corresponds to Formula 3 and comprises sulfobetaine orcarboxybetaine pendant groups. In one especially preferred embodiment,the grafted polymeric material comprises repeat units derived fromsulfobetaine methacrylate, sulfobetaine acrylate, sulfobetaineacrylamide, sulfobetaine methacrylamide, carboxybetaine methacrylate,carboxybetaine acrylate, carboxybetaine acrylamide, or carboxybetainemethacrylamide monomers. In general, the height and any branching of thegrafted polymeric material can help to overcome surface irregularitiesand defects, and increased branching may reduce the ability of foulingmaterials to penetrate the non-fouling layer.

Polymerization

The polymeric surface modifications of the present disclosure may beformed by synthetic means including, but not limited to, free radicalpolymerization, ionic polymerization, atom transfer radicalpolymerization (ATRP), nitroxide mediated polymerization (NMP),reversible addition-fragmentation polymerization (RAFT), ring openingmetathesis polymerization (ROMP), telluride mediated polymerization(TERP) or acyclic diene metathesis polymerization (ADMET), and UV,thermal, or redox free radical initiated polymerization. In a preferredembodiment, the polymer is formed using an oxidizing agent and areducing agent, in combination, i.e., a redox pair, as thepolymerization initiator in a redox free radical polymerization.

In some embodiments, it is preferable that initiators and ligands oftenused in ATRP such as bromine- and chlorine-containing initiators andligands such as bipyridine are not used in the process as they may benon-biocompatible or toxic at certain levels. Representative bromide orchloride containing compounds or residues to be avoided includetert-butyl 2-bromopropionate, tert-butyl 2-bromoisobutyrate,hydroxyethyl 2-bromopropionate, hydroxyethyl 2-bromoisobutyrate, vinylchloroacetate, allyl chloroacetate, glycidyl 2-bromopropionate, glycidyl2-bromoisobutyrate, 4-cyanobenzyl bromide, bromoacetonitrile and2-bromocyanopropane. In further embodiments, it is preferred not to havea detectable level of bipyridine in the polymer modified article or inaqueous or organic extractions of the polymer modified article. Infurther embodiments, it is preferred not to have a detectable level ofbromine in the polymer modified article or in aqueous or organicextractions of the polymer modified article. Bipyridine and bromine canbe detected, for example, with HPLC or UV analysis. In some embodiments,it is preferable to have a surface modified contact lens that does notcontain any residual bromide. Preferably, the concentration of bromideor chloride is less than 1 ppm, 5 ppm, 10 ppm, or 50 ppm. Preferably, nobromide or chloride could be detected by XPS, SEM-EDS, and otherelemental analysis methods.

As noted above, the general procedure described herein can be modifiedas necessary to accommodate different substrate materials, initiatorssystems, and/or monomer compositions. In some embodiments, for example,it may be desirable to incorporate high concentrations of the initiatorinto and/or onto the substrate or undercoating layer. High initiatorconcentrations may result in highly densely coated surfaces whichimproves the non-fouling activity of the composition. For example,highly densely coated surfaces contain polymer chains that reducepenetration of fouling molecules into the coating. Without being boundto any particular theory it is presently theorized that a reservoir ofinitiator incorporated in the substrate may enhance re-initiation andbranching of non-fouling polymer from the surface and near the surfaceof the substrate. This re-initiation, in turn, may increase thethickness of the non-fouling polymer (in other words, the distance thenon-fouling polymer stretches above the substrate in a direction normalto the substrate surface) as well as the degree of branching.

In accordance with the present disclosure, processes described hereininvolve applying a surface modification to medical device, such as acontact lens (e.g., a silicone hydrogel contact lens). For instance, theprocesses generally involve contacting the contact lens with apolymerization solution as described herein. In one embodiment,contacting of a contact lens with a polymeric surface modificationsolution can occur by dipping or submerging the lens into the solutionor by spraying the lens with the solution. One exemplary surfacemodification process involves solely dip-modification and optionallydip-rinsing steps. Another exemplary surface modification processinvolves solely spray-modification and spray-rinsing steps. However, anumber of alternatives involve various combinations of spray- anddip-modification and/or rinsing steps may be designed by a person havingordinary skill in the art.

For example, a solely dip-modification process for forming a surfacemodification as described herein involves the steps of: (a) immersing acontact lens in a surface modification solution; and (b) optionallyrinsing the mold half by immersing it in water; and (c) optionallyrepeating steps (a) to (b) for a number of times. A thicker surfacemodification can be produced by repeating steps (a) to (b) preferablyfor a number of times. Other steps may also be involved.

In some embodiments, incorporation of initiator into the substrateenables polymeric material to be grafted from the substrate surface andfrom within a near-surface zone beneath the substrate surface. Themaximum depth to which near-surface zone extends, i.e., the distance ofthe lower boundary of the near-surface zone as measured from thesubstrate surface is, at least in part, a function of the initiator andthe technique used to incorporate initiator in the substrate. Typically,however, it is generally preferred that the lower boundary not begreater than 1%, 5%, 10%, 20%, 30%, 45% of the thickness of the contactlens. Similarly, the minimum depth of near-surface zone, i.e., thedistance of the upper boundary of the near-surface zone from thesubstrate surface is, at least in part, also a function of the initiatorand the technique used to incorporate initiator in the substrate. By wayof example, the upper boundary may be at least 1% from the substratesurface. By way of further example, the upper boundary may be at least45% from the substrate surface.

Typically, however, it is generally preferred that the lower boundarynot be greater than 1 micrometer as a dry material or 20 micrometers asa hydrated material from the substrate surface. By way of example, thelower boundary may not be greater than 15 micrometers from the hydratedsubstrate surface. By way of further example, the lower boundary may notbe greater than 10 micrometers from the hydrated substrate surface.Similarly, the minimum depth of near-surface zone, i.e., the distance ofthe upper boundary of the near-surface zone from the substrate surfaceis, at least in part, also a function of the initiator and the techniqueused to incorporate initiator in the substrate. Typically, however, theupper boundary will be at least 0.1 micrometers from the substratesurface. By way of example, the upper boundary may be at least 0.2micrometers from the substrate surface. By way of further example, theupper boundary may be at least 0.3 micrometers from the substratesurface.

To induce small polymerization initiator molecules to concentrate at ornear the substrate surface, where polymerization is initiated andpropagated, polymerization mixture solvent systems with surface tensionsof a magnitude differing from the surface energy of the substrate andone or more polymerization initiators having limited solubility in thepolymerization mixture solvent system are selected. The surfaces of thesubstrate from which the non-fouling material is to be grafted surfacesmay be hydrophobic or hydrophilic, and the polymerization mixturesolvent system may be aqueous, comprise polar organic solvents, aqueousmixtures of polar organic solvents, or aqueous mixtures of any organiccompound designed to modify the surface tension of aqueous solutions.Optionally, for hydrophobic substrates, hydrophobic initiator(s) andhydrophilic solvent systems, e.g., aqueous media are selected.Preferably, if the substrate is hydrophilic, at least one hydrophilicinitiator and a non-polar organic solvent system is selected.

In the embodiments in which the initiator(s) are incorporated into thesubstrate, they preferably have limited solubility in the solvent systemcomprised by the polymerization mixture and include any of theinitiators identified herein. In general, it is preferred that theincorporated initiator(s) have a 10 hour T1/2 decomposition temperatureof 25-175° C. In one particular embodiment, the incorporatedinitiator(s) have a 10 hour T1/2 decomposition temperature of 70-130° C.Advantageously, having a 10 hour T1/2 decomposition temperature of70-130° C. tends to increase the density of interfacial initiationevents from the redox reaction and effectively outcompete thermalinitiation.

As described elsewhere herein, the initiator may comprise a redox pair;in such embodiments, at least one member of such pair has such a limitedsolubility in the polymerization mixture solvent system. In oneembodiment, both members of the redox pair have limited solubility inthe polymerization mixture solvent system. In an alternative embodiment,one member of the pair is soluble in the polymerization mixture solventsystem but the other has limited solubility in the polymerizationmixture solvent system. Without being bound to any particular theory, itis presently believed that when one member of a redox pair is soluble inthe polymerization mixture solvent system and the other has limitedsolubility in the polymerization mixture solvent system, the two arephase separated and initiation is enhanced at the interface of the twophases which tends to decrease solution polymerization and increasegrafting at or near the substrate surface. Thus, for example, eithermember of the redox pair may be hydrophobic and either member of thepair may be hydrophilic, provided at least one of the members haslimited solubility in the polymerization mixture solvent system. In onepreferred embodiment, a hydrophobic oxidizer is paired with ahydrophilic reducing agent. In another preferred embodiment, ahydrophilic oxidizer is paired with a hydrophobic reducing agent. Forexample, in one embodiment, the redox pair comprises a peroxide and areducing agent wherein the peroxide has limited solubility in thepolymerization solvent system and the reducing agent has high solubilityin the polymerization solvent system. By way of further example, incertain embodiments, the peroxide has a log P partition coefficientgreater than or equal to 3 for hydrophobic substrates and phases and alog P partition coefficient less than 3 for hydrophilic substrates andphases. By way of further example, in certain embodiments, the peroxidehas a log P partition coefficient greater than or equal to 5 forhydrophobic substrates and phases and a log P partition coefficient lessthan 1 for hydrophilic substrates and phases. By way of further example,in certain embodiments, the peroxide has a log P partition coefficientgreater than or equal to 7 for hydrophobic substrates and phases and alog P partition coefficient less than −1 for hydrophilic substrates andphases. By way of further example, in certain embodiments, the peroxidehas a log P partition coefficient greater than or equal to 9 forhydrophobic substrates and phases and a log P partition coefficient lessthan −3 for hydrophilic substrates and phases.

In one embodiment, an initiator is incorporated into the substrate byinitially incorporating an initiator-precursor into the substrate andactivating the initiator-precursor to an initiator.

Imbibing With Initiator

In accordance with one aspect of the present invention, thepolymerization initiator(s) may be incorporated into and/or onto thesubstrate by various techniques. In one such method, the substrate(including, in some embodiments, substrates having precoat or undercoatas previously described) is imbibed with the polymerization initiator;that is, the polymerization initiator is absorbed into the substrate. Inone embodiment, the initiator(s), i.e., an initiator or a mixture ofdifferent initiators, is introduced into and/or onto the substrate'ssurface by physio-adsorption, wherein the initiator is dissolved in asolvent or combination of solvents and the substrate (with or without anundercoating layer) is submerged in the mixture for a time and at atemperature to achieve sufficient absorption by the substrate. Thesubstrate is allowed to swell ultimately imbibing initiator into thesubstrate. In general, the amount of initiator incorporated into asubstrate during the soak will, at least in part, be a function of the,solubility of the initiator in the solvent system, solubility of theinitiator in the substrate as well as the soak time, temperature andconcentration of the initiator in the solution, as well as the chemicalcomposition of the substrate and the initiator. In some embodiments, thesubstrate is imbibed with the initiator and also imbibed with themonomer (as described below); for example, the initiator and the monomercan be combined in a single solution (optionally, but preferably,including a solvent or solvent system) and the substrate immersed in thesolution.

In a preferred embodiment, the surface of the substrate to be imbibedwith the polymerization initiator(s) comprises a polymer, natural orsynthetic. In an alternative embodiment, the substrate is an imbibablematerial selected from among polymers, natural or synthetic, biologicaltissues, living or dead, woven non-woven fibers, and combinationsthereof. Certain (uncoated) substrates such as a metal, ceramic, glass,and semi-metallic substrates lack the capacity to absorb sufficientinitiator. In general, therefore, for these substrates it is preferredto precoat the surface of the metal, ceramic, glass or semi-metallicsubstrate with an undercoating or precoating, from which the polymericmaterial may be grafted. For example, metal, ceramic, glass, andsemi-metallic substrates may be precoated with a polymer selected frompolyamide, polyamine, polyanhydride, polyazine, poly(carbonate),polyester, polyether, polyetheretherketone (PEEK), polyguanidine,polyimide, polyketal, poly(ketone), polyolefin, poly(orthoester),polyphosphazine, polysaccharide, polysiloxane, polysulfone, polyurea,polyurethane, halogenated polymer, silicone, aldehyde crosslinked resin,epoxy resin, phenolic resin, latex, or a copolymer or blend thereof, andthe precoated substrate is then imbibed as previously described.

The quantity of initiator introduced to the substrate can be controlledby changing the concentration of the initiator in the solvent solutionand/or by changing the amount of time the substrate is allowed to soakin the initiator solution during one initiator imbibing period or byrepeating any number of initiator imbibing periods as required.Temperature is not narrowly critical, with temperatures in the range ofroom temperature to elevated temperatures being typical. When utilizingmultiple periods of initiator imbibing, the initiator used in thesubsequent imbibing periods can be the same as, different from, or amixture with the initiator used in the previous initiator imbibingperiod. In general, the substrate is immersed in theinitiator-containing solution for at least several seconds beforepolymerization is initiated. In some embodiments, the substrate isimmersed in the initiator-containing solution for longer times. Forexample, the substrate may be immersed in the initiator-containingsolution for at least several minutes. By way of further example, thesubstrate may be immersed in the initiator-containing solution for atleast about 15 minutes before polymerization is initiated. In someembodiments, the substrate will be immersed in the initiator-containingsolution for at least 1 hour at room temperature or elevatedtemperatures for initiators having a 10 hour T1/2 decompositiontemperature of 70-130° C. before polymerization is initiated. In furtherembodiments, the substrate will be immersed in the initiator-containingsolution for at least 2 hours before polymerization is initiated. In yetfurther embodiments, the substrate will be immersed in theinitiator-containing solution for at least 16 hours beforepolymerization is initiated. Depending upon the time, temperature andconcentration of initiator in the initiator-containing solution, aconcentration gradient of initiator in the substrate may be established.In some embodiments, it may be preferable to have a higher concentrationof initiator in the substrate nearer to the surface. As noted, theinitiator may be present in a range of concentrations in theinitiator-containing solution. In general, the concentration of theinitiator in the initiator-containing solution will be at least 0.01% byweight. For example, in some embodiments, the concentration of theinitiator will generally be at least 0.1% by weight. In someembodiments, the concentration will be even greater, e.g., at least 0.5%by weight. In some embodiments, the concentration will be even greater,e.g., at least 1% by weight. In some embodiments, the concentration willbe even greater, e.g., at least 10% by weight. In certain exemplaryembodiments, the concentration of the initiator in theinitiator-containing solution will be in the range of about 0.2 to about1% by weight. In certain exemplary embodiments, the concentration of theinitiator in the initiator-containing solution will be in the range ofabout 0.2 to about 10% by weight. In certain exemplary embodiments, theconcentration of the initiator in the initiator-containing solution willbe in the range of about 0.5 to about 5% by weight. In certain exemplaryembodiments, the concentration of the initiator in theinitiator-containing solution will be in the range of about 0.75 toabout 3% by weight. In each of these embodiments, the initiator ispreferably one of the UV, thermal or redox initiators describedelsewhere herein.

In some embodiments, the initiator is dissolved in a solvent;preferably, the solvent is an aqueous solvent. A solvent can be water,any appropriate organic solvent, a mixture of water and one or morewater soluble or water miscible organic solvents, or a mixture ofseveral organic solvents. Any known suitable solvents can be used, solong as they can dissolve the initiator. Exemplary solvents include,without limitation, water, acetone, alcohols (e.g., methanol, ethanol,propanol, isopropanol, etc.), glycols, ketones, esters, cyclopentanone,cyclohexanone, tetrahydrofuran (THF), acetone, methyl-2-pyrrolidone,dimethyl formamide, acetophenone, methylene dichloride, dimethylsulfoxide, gamma-butyrolactone, ethylene dichloride, isophorone,o-dichlorobenzene, tetrahydrofuran, diacetone alcohol, methyl ethylketone, acetone, 2-nitropropane, ethylene glycol monoethyl ether,propylene carbonate, cyclohexanol, chloroform, trichloroethylene,1,4-dioxane, ethyl acetate, ethylene glycol monobutyl ether,chlorobenzene, nitroethane, ethylene glycol monomethyl ether, butylacetate, 1-butanol, methyl isobutyl ketone, nitromethane, toluene,ethanol, diethylene glycol, benzene, diethyl ether, ethanolamine, carbontetrachloride, propylene glycol, hexane, ethylene glycol, and formamide.Examples of water soluble or water miscible organic components includewithout limitation, ethylene glycol, propylene glycol, diethyleneglycol, glycerine, dipropylene glycol, polyethylene glycol,polypropylene glycol, amides, ethers, urea, substituted ureas,carboxylic acids and their salts, esters, alcohols, organosulfides,organosulfoxides, sulfones (such as sulfolane), alcohol derivatives,carbitol, butyl carbitol, cellosolve, tripropylene glycol monomethylether, ether derivatives, amino alcohols, ketones,N-methylpyrrolidinone, 2-pyrrolidinone, cyclohexylpyrrolidone,hydroxyethers, sulfoxides, lactones, polyelectrolytes, methylsulfonylethanol, tetrahydrofuran (THF), imidazole, betaine, and otherwater soluble or water miscible materials, as well as mixtures thereof.

As a result of the imbibing process, the imbibed substrate may containabout 0.001% by weight initiator. In some embodiments, the imbibedsubstrate will contain greater amounts of initiator, e.g., at leastabout 0.01% by weight. For example, in some embodiments the imbibedsubstrate will contain at least about 0.1% by weight. By way of furtherexample, in some embodiments the imbibed substrate will contain about0.05% to about 2% by weight initiator. By way of further example, insome embodiments the imbibed substrate will contain about 0.1% to about1% by weight initiator. By way of further example, in some embodimentsthe imbibed substrate will contain about 0.2% to about 0.5% by weightinitiator. By way of further example, in some embodiments the imbibedsubstrate will contain about 1% to about 10% by weight initiator.Typically, however, the imbibed substrate will contain less than about20% by weight initiator. In each of these embodiments, the initiator ispreferably one of the UV, thermal or redox initiators describedelsewhere herein. The solvent used to imbibe the substrate withinitiator may have the capacity to swell the substrate (or at least theportion of the substrate to be imbibed with initiator) to variousdegrees. Typically, the imbibing solvent has a capacity to swell thesubstrate (or at least the portion of the substrate to be imbibed withinitiator) less than 900% by volume at room temperature and ambientpressure. For example, in one such embodiment, the imbibing solvent hasa capacity to swell the substrate (or at least the portion of thesubstrate to be imbibed with initiator) less than 750% by volume. By wayof further example, in one such embodiment, the imbibing solvent has acapacity to swell the substrate (or at least the portion of thesubstrate to be imbibed with initiator) less than 500% by volume. By wayof further example, in one such embodiment, the imbibing solvent has acapacity to swell the substrate (or at least the portion of thesubstrate to be imbibed with initiator) less than 250% by volume. By wayof further example, in one such embodiment, the imbibing solvent has acapacity to swell the substrate (or at least the portion of thesubstrate to be imbibed with initiator) less than 100% by volume. By wayof further example, in one such embodiment, the imbibing solvent has acapacity to swell the substrate (or at least the portion of thesubstrate to be imbibed with initiator) less than 100% by volume. By wayof further example, in one such embodiment, the imbibing solvent has acapacity to swell the substrate (or at least the portion of thesubstrate to be imbibed with initiator) less than 25% by volume.

In a preferred embodiment, the imbibed substrate is preferably washedusing a solvent, optionally with a solvent that swells that substrate,and optionally dried. In other embodiments, the substrate is washed withsolvents, which may be the same or different from the imbibing solvents,or the substrate may not be washed. For example, the wash solvent mayswell the substrate, shrink the substrate, or neither. In oneembodiment, the substrate is dried, partially dried or not dried.Optionally, there may be a solvent exchange.

Imbibing With Monomer

In accordance with another aspect of the present invention, interfacialgrafting of a monomer (e.g., a hydrophilic monomer) to the surface of acontact lens is facilitated by saturating the lenses with monomer priorto initiation of the polymerization reaction. This method involves theuse of two reaction solutions. After saturating the lenses with monomer,a new solution is created with a lesser amount of monomer. This aspectcontrols the reaction to the surface of contact lenses and decreases theamount of monomer required to achieve modification of the lens surface.During the surface modification reaction, monomer can polymerize insolution to form ungrafted homopolymer. The homopolymer generally has alow solubility in pure water and can precipitate in the reactionsolution, creating cloudiness both in solution and on the surface of thelens. The use of a minimum amount of monomer is preferred to limithomopolymer precipitation, as well as to reduce cost and chemical waste.By saturating the contact lens with a hydrophilic monomer solution priorto the initiation of the polymerization reaction, the polymerizationproceeds at the lens surface which is the interface of monomer (withinthe lens) and initiator (outside the lens), facilitating a surfacereaction. Alternately, for UV-initiated surface modification reactions,a lens pre-saturated with the hydrophilic monomer solution can bedirectly irradiated after removal from the monomer solution to initiatethe polymerization reaction without using unreacted initiator.Preferably, there is no excess monomer in the bulk reaction solution,thereby limiting homopolymer precipitation and cloudiness in solutionand on the surface of the lens. In some embodiments, the substrate isimbibed with the monomer and also imbibed with the initiator (asdescribed above); for example, the monomer and the monomer can becombined in a single solution (optionally, but preferably, including asolvent or solvent system) and the substrate immersed in the solution.

The monomers may be incorporated into and/or onto the substrate byvarious techniques. In one such method, the substrate (e.g., a contactlens as previously described) is imbibed with the monomer; that is, thepolymerization initiator is absorbed into the substrate. In oneembodiment, the monomer(s), i.e., a monomer or a mixture of differentmonomers, is introduced into and/or onto the substrate's surface byphysio-adsorption, wherein the monomer is dissolved in a solvent orcombination of solvents and the substrate is submerged in the mixturefor a time and at a temperature to achieve sufficient absorption by thesubstrate. The substrate is allowed to swell ultimately imbibing monomerinto the substrate. In general, the amount of monomer incorporated intoa substrate during the soak will, at least in part, be a function ofthe, solubility of the monomer in the solvent system, solubility of themonomer in the substrate as well as the soak time, temperature andconcentration of the monomer in the solution, as well as the chemicalcomposition of the substrate and the monomer.

In some embodiments, the monomer is dissolved in a solvent; preferably,the solvent is an aqueous solvent. A solvent can be water, anyappropriate organic solvent, a mixture of water and one or more watersoluble or water miscible organic solvents, or a mixture of severalorganic solvents. Any known suitable solvents can be used, so long asthey can dissolve the electrolyte (and/or the monomers and/or theinitiator). Exemplary solvents include, without limitation, water,acetone, alcohols (e.g., methanol, ethanol, propanol, isopropanol,etc.), glycols, ketones, esters, cyclopentanone, cyclohexanone,tetrahydrofuran (THF), acetone, methyl-2-pyrrolidone, dimethylformamide, acetophenone, methylene dichloride, dimethyl sulfoxide,gamma-butyrolactone, ethylene dichloride, isophorone, o-dichlorobenzene,tetrahydrofuran, diacetone alcohol, methyl ethyl ketone, acetone,2-nitropropane, ethylene glycol monoethyl ether, propylene carbonate,cyclohexanol, chloroform, trichloroethylene, 1,4-dioxane, ethyl acetate,ethylene glycol monobutyl ether, chlorobenzene, nitroethane, ethyleneglycol monomethyl ether, butyl acetate, 1-butanol, methyl isobutylketone, nitromethane, toluene, ethanol, diethylene glycol, benzene,diethyl ether, ethanolamine, carbon tetrachloride, propylene glycol,hexane, ethylene glycol, and formamide. Examples of water soluble orwater miscible organic components include without limitation, ethyleneglycol, propylene glycol, diethylene glycol, glycerine, dipropyleneglycol, polyethylene glycol, polypropylene glycol, amides, ethers, urea,substituted ureas, carboxylic acids and their salts, esters, alcohols,organosulfides, organosulfoxides, sulfones (such as sulfolane), alcoholderivatives, carbitol, butyl carbitol, cellosolve, tripropylene glycolmonomethyl ether, ether derivatives, amino alcohols, ketones,N-methylpyrrolidinone, 2-pyrrolidinone, cyclohexylpyrrolidone,hydroxyethers, sulfoxides, lactones, polyelectrolytes, methylsulfonylethanol, tetrahydrofuran (THF), imidazole, betaine, and otherwater soluble or water miscible materials, as well as mixtures thereof.

The quantity of monomer introduced to the substrate can be controlled bychanging the concentration of the monomer in the solvent solution and/orby changing the amount of time the substrate is allowed to soak in themonomer solution during one monomer imbibing period or by repeating anynumber of monomer imbibing periods as required. Temperature is notnarrowly critical, with temperatures in the range of room temperature toelevated temperatures being typical (e.g., −15° C. to 80° C.). Whenutilizing multiple periods of monomer imbibing, the monomer used in thesubsequent imbibing periods can be the same as, different from, or amixture with the monomer used in the previous monomer imbibing period.Thus, the monomer-containing solution can be re-used for multiple orserial applications, typically until the polymer concentration isgreater than 1%, greater than 2%, greater than 10%, or greater than 20%by weight of the solution. In general, the substrate is immersed in themonomer-containing solution for at least several seconds (e.g., 30seconds). In some embodiments, the substrate is immersed in themonomer-containing solution for longer times. For example, the substratemay be immersed in the monomer-containing solution for at least severalminutes. By way of further example, the substrate may be immersed in themonomer-containing solution for at least about 5 minutes, 10 minutes, or15 minutes. In some embodiments, the substrate will be immersed in themonomer-containing solution for at least 1 hour, 2 hours, 4 hours, or 6hours. In further embodiments, the substrate will be immersed in themonomer-containing solution for at least 6 hours, 8 hours, or 12 hours.In yet further embodiments, the substrate will be immersed in themonomer-containing solution for at least 14 hours, 16 hours, 18 hours,20 hours, 22 hours, or 24 hours. In one preferred embodiment, thesubstrate is immersed in the monomer-containing solution for 1 hour. Insome embodiments, the initiator is present during the monomer imbibing(i.e., the monomer and the initiator are co-imbibed). In otherembodiments, the initiator is added after the monomer imbibing period oftime.

As a result of the imbibing process, the imbibed substrate may containfrom about 0.01% to about 50% by weight monomer. In some embodiments,for example, the imbibed substrate will contain greater amounts ofmonomer, e.g., at least about 0.1% by weight, at least about 0.5% byweight, or at least about 1% by weight monomer. By way of furtherexample, in some embodiments the imbibed substrate will contain at leastabout 2% by weight, at least about 5% by weight, or at least about 10%by weight monomer. By way of further example, in some embodiments, theimbibed substrate will contain about 0.01% to about 2% by weightmonomer. By way of further example, in some embodiments the imbibedsubstrate will contain about 0.1% to about 1% by weight monomer. By wayof further example, in some embodiments the imbibed substrate willcontain about 0.2% to about 0.5% by weight monomer. By way of furtherexample, in some embodiments the imbibed substrate will contain about 1%to about 10% by weight monomer. By way of further example, in someembodiments the imbibed substrate will contain about 1% to about 20% byweight monomer. By way of further example, in some embodiments theimbibed substrate will contain about 5% to about 25% by weight monomer.By way of further example, in some embodiments the imbibed substratewill contain about 10% to about 50% by weight monomer. Typically,however, the imbibed substrate will contain less than about 20% byweight monomer.

By way of example, a contact lens can be pre-equilibrated in 10%, 25%,or 50% SBMA aqueous solution for 30 seconds to 2 hours (preferably 1hour) before putting it into a reaction mixture including an initiator(e.g., 0.5 to 200 mM Ce(IV), preferably about 5 mM). The reaction isthen performed at 25-80° C. (e.g., 40-60° C.) for 1 hour. The contactlens is also preferably be pre-soaked in water for 40-60 minutes beforeadding to the reaction; this can help retain the shape and clarity ofthe lens, as dry lenses placed directly into the reaction mixture tendto exhibit poor clarity and shape upon completion of the reaction. Byway of another example, pre-soaking in 5% SBMA in 0.15M NaCl prior toreaction with 5% SBMA and 1 mM Ce(IV) in 0.15M NaCl at 60° C. for 2.5 h,the lens exhibited good shape and clarity after rinse, while the lenswithout pre-equilibrium was not good in shape and clarity. The soakingsolution could be reused until higher than 1%, 2%, 10%, or 20% polymerwas found in the solution by NMR.

Ionic Strength

In accordance with another aspect of the present disclosure, the surfacemodification is carried out in the presence of an electrolyte. In oneembodiment, for example, electrolytes such as monovalent salts are addedto the reaction solution to increase the ionic strength and minimizezwitterionic polymer precipitation. Moreover, some salts, such as KCl,can additionally act to reduce the formation of high molecular weighthomopolymer, which will also maintain a homogenous reaction solution andprevent cloudiness both in solution and on the surface of the lens.

In one embodiment, for example, the surface modification solutionincludes an electrolyte along with the monomer and the initiator asdescribed herein. In general, the electrolyte can be added at any stageof the reaction or may be present throughout the reaction and anypre-conditioning of the substrate. By way of example, the electrolytemay be present during a monomer imbibing period, an initiator imbibingperiod, a combination monomer-initiator imbibing period, or may be addedafter a monomer and/or initiator imbibing period (e.g., at or shortlyafter the commencement of the polymerization reaction). Suitableelectrolytes are those that increase the ionic strength and minimize orprevent precipitation of other solution components (e.g., a zwitterionicpolymer). The electrolyte typically comprises a salt having a cationiccomponent and an anionic component. Suitable cations may be monovalentor multivalent, may be organic or inorganic, and include, for example,sodium, potassium, lithium, calcium, magnesium, cesium, and lithiumcations, as well as mono-, di- tri- or quaternary ammonium or pyridiniumcation. Suitable anions may be a monovalent or multivalent, may beorganic or inorganic, and include, for example, chloride, sulfate,nitrate, nitrite, carbonate, citrate, cyanate acetate, benzoate,tartarate, oxalate, phosphate, and phosphonate anions. Suitableelectrolytes include, for example, salts of multivalent anions withmonovalent cations, such as potassium pyrophosphate, potassiumtripolyphosphate, and sodium citrate, salts of multivalent cations withmonovalent anions, such as calcium chloride, calcium bromide, zinchalides, barium chloride, and calcium nitrate, and salts of monovalentcations with monovalent anions, such as sodium chloride, potassiumchloride, potassium iodide, sodium bromide, ammonium bromide, alkalimetal nitrates, and ammonium nitrates. In one preferred embodiment, theelectrolyte comprises a monovalent cationic component and a monovalentanionic component, such as, for example, sodium chloride or potassiumchloride.

The electrolyte may additionally or alternatively comprise a buffer.Representative buffers include acetates, phosphates, and citrates and anonexclusive list of these and other particular buffers is as follows:phosphate buffered saline (PBS), borate, Na-Acetate;N-2-Hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES);Na-Cacodylate; Na-Citrate; Na-Succinate; Na-K-Phosphate;Tris(hydroxymethyl)aminomethane (TRIS); TRIS-Maleate; Imidazole-Maleate;BisTrisPropane; N-cyclohexyl-3-aminopropanesulfonic acid (CAPS);N-cyclohexyl-2-hydroxyl-3-aminopropanesulfonic acid (CAPSO);3-[(3-Cholamidopropyl)dimethylammonio]propanesulfonic acid (CHAPS),2-(N-morpholino)ethanesulfonic acid (MES), and imidizole buffers.

Typically, the electrolyte (and/or other reactants, such as the monomerand/or the initiator) is dissolved in a solvent. A solvent can be water,any appropriate organic solvent, a mixture of water and one or morewater soluble or water miscible organic solvents, or a mixture ofseveral organic solvents. Any known suitable solvents can be used, solong as they can dissolve the electrolyte (and/or the monomers and/orthe initiator). Exemplary solvents include, without limitation, water,acetone, alcohols (e.g., methanol, ethanol, propanol, isopropanol,etc.), glycols, ketones, esters, cyclopentanone, cyclohexanone,tetrahydrofuran (THF), acetone, methyl-2-pyrrolidone, dimethylformamide, acetophenone, methylene dichloride, dimethyl sulfoxide,gamma-butyrolactone, ethylene dichloride, isophorone, o-dichlorobenzene,tetrahydrofuran, diacetone alcohol, methyl ethyl ketone, acetone,2-nitropropane, ethylene glycol monoethyl ether, propylene carbonate,cyclohexanol, chloroform, trichloroethylene, 1,4-dioxane, ethyl acetate,ethylene glycol monobutyl ether, chlorobenzene, nitroethane, ethyleneglycol monomethyl ether, butyl acetate, 1-butanol, methyl isobutylketone, nitromethane, toluene, ethanol, diethylene glycol, benzene,diethyl ether, ethanolamine, carbon tetrachloride, propylene glycol,hexane, ethylene glycol, and formamide. Examples of water soluble orwater miscible organic components include without limitation, ethyleneglycol, propylene glycol, diethylene glycol, glycerine, dipropyleneglycol, polyethylene glycol, polypropylene glycol, amides, ethers, urea,substituted ureas, carboxylic acids and their salts, esters, alcohols,organosulfides, organosulfoxides, sulfones (such as sulfolane), alcoholderivatives, carbitol, butyl carbitol, cellosolve, tripropylene glycolmonomethyl ether, ether derivatives, amino alcohols, ketones,N-methylpyrrolidinone, 2-pyrrolidinone, cyclohexylpyrrolidone,hydroxyethers, sulfoxides, lactones, polyelectrolytes, methylsulfonylethanol, tetrahydrofuran (THF), imidazole, betaine, and otherwater soluble or water miscible materials, as well as mixtures thereof.In one embodiment, the solvent is water. In another embodiment, thesolvent is a mixture of solvents comprising 5%, 10%, or 20% methanol inwater.

In some embodiments, for example, the reaction solution comprises fromabout 10 mM to about 10 M of the electrolyte (or a combination ofelectrolytes). For example, the reaction solution may comprise fromabout 100 mM to about 5 M electrolyte. By way of another example, thereaction solution may comprise 150 mM, 200 mM, 250 mM, 300 mM, 350 mM,400 mM, 450 mM, 500 mM, 750 mM, 1M, 2 M, 3 M, 4 M, or 5 M electrolyte.In one particular embodiment, the electrolyte is present in the reactionsolution at a concentration of 150 mM to about 5 M. In anotherparticular embodiment, the electrolyte is 150 mM sodium chloride.

In preferred embodiments, the reaction solution is clear and free ofhomopolymer. By one method to quantify the cloudiness of the reactionsolution, the optical density at 600 nm of the reaction solution aroundthe contact lens is less than about 0.2. For example, the opticaldensity at 600 nm may be less than about 0.1, less than about 0.05, orless than about 0.01. In one embodiment, the optical densitymeasurements in each of the foregoing examples and embodiments recitedin this paragraph are taken at the UV polymerization reaction conditionsdiscussed herein or at a reaction temperature of about 60° C. In anotherembodiment, the optical density measurements in each of the foregoingexamples and embodiments recited in this paragraph are taken at roomtemperature. In another embodiment, the optical density measurements ineach of the foregoing examples and embodiments recited in this paragraphare taken at 0° C. after placing the sample vial in an an ice-waterbath.

The polymer surface modification reaction is initiated through the useof an initiator. In general, any known suitable initiators can be usedin the processes described herein, which involve contacting or mixingthe initiator, monomer, and the substrate, or otherwise includinginitiator in the reaction mixture. A person skilled in the art will knowwell how to select an initiator for initiating a polymerization. Forexample, one or more species of ultraviolet (UV) initiators, one or morespecies of thermal initiators, and/or one or more species of redoxinitiators may be employed.

In accordance with one embodiment, initiator is incorporated into thesubstrate by imbibing the substrate or depositing a coating containingthe initiator onto the substrate. The incorporated initiator maycomprise one initiator species, or more than one initiator species. Forexample, one or more species of ultraviolet (UV) initiators, one or morespecies of thermal initiators, and/or one or more species of redoxinitiators may be incorporated into the substrate. More specifically, inone presently preferred embodiment, the initiator(s) are/is incorporatedinto the near-surface zone between its upper and lower boundaries asdescribed elsewhere herein. Based upon experimental evidence to date,and without being bound to any particular theory, it appears that theincorporated initiator permits a grafting of the polymeric material fromwithin the near-surface zone as well as the substrate surface.

Regardless of the theory, it is generally preferred that the amount ofinitiator incorporated into the substrate be sufficient to enable itsdetection in the substrate, prior to polymerization, and detection of itor a degradation product thereof in the substrate post-polymerization.In general, extractions can use both nonpolar and polar solvents. Forexample, extraction solvents such as water, acetone or ethanol; and/orother extraction solvents in which the solubility of the initiatorand/or its degradation products is at least 1 mg/L. The extractionshould be carried out for a sufficient time such that the change inconcentration of the extract is not increasing more than 5% per hour.Alternatively, extraction until the amount of extracted material in asubsequent extraction is less than 10% of that detected in the initialextraction, or until there is no analytically significant increase inthe cumulative extracted material levels detected. Exemplary extractionconditions include: 37° C. for 72 h; 50° C. for 72 h; 70° C. for 24 h;and 121° C. for 1 h. Exemplary extraction ratio includes 6 cm²/mLsurface area/volume and/or 0.2 g sample/mL. In some instances, completedissolution of the substrate may be appropriate. Materials shall be cutinto small pieces before extraction to enhance submersion in the extractmedia, for example, for polymeric substrates approximately 10 mm×50 mmor 5 mm×25 mm are appropriate.

Examples of the instrumentation used for analysis includeshigh-performance liquid chromatography-photo-diode array detection-massspectrometry (HPLC-PDA-MS) for organics analysis; gaschromatography-mass spectrometry (GC-MS) for organics analysis;inductively coupled plasma-optical emission spectroscopy or massspectrometry (ICP-OES or ICP-MS) for metals analysis; and ionchromatography (IC) for inorganics and ion analysis. More advanced MSdetectors such as time-of-flight (TOF) can also be used to obtainaccurate mass information. Hexane and alcohol extractions are analyzed,for example by GC-MS and HPLC. Water and alcohol extractions areanalyzed, for example by HPLC.

The initiator or its degradation products may be quantified and/ordetected in the substrate or grafted polymer by the previously describedmethods. These include FTIR-ATR, electron spectroscopy for chemicalanalysis (ESCA, also called X-ray photoelectron spectroscopy, XPS),Secondary Ion Mass Spectrometry (SIMS), and surface-enhanced Ramanspectroscopy (SERS). For example, peroxide may be detectedspectrophotometically using any of the following three methods: theiodide method (oxidation of sodium iodide by peroxides in the presenceof ferric chloride), the DPPH method (treatment with1,1-diphenyl-2-picrylhydrazyl, a radical scavenger, to decompose theperoxides), or the peroxidase method (reduction with glutathione,catalyzed by glutathione peroxidase, followed by measuring the coupledoxidation of NADPH in the presence of glutathione reductase). See, forexample, Fujimoto et al., Journal of Polymer Science Part A: PolymerChemistry, Vol. 31, 1035-1043 (1993).

Similarly, the initiator(s) and/or the degradation products thereof mayalso be extracted from the substrate/grafted polymer using a suitablesolvent such as water, acetone or ethanol, and quantified and/ordetected in the substrate or grafted polymer by the previously describedmethods. These include FTIR-ATR, electron spectroscopy for chemicalanalysis (ESCA, also called X-ray photoelectron spectroscopy, XPS),Secondary Ion Mass Spectrometry (SIMS), and surface-enhanced Ramanspectroscopy (SERS). For example, peroxide may be detectedspectrophotometically using any of the following three methods: theiodide method (oxidation of sodium iodide by peroxides in the presenceof ferric chloride), the DPPH method (treatment with1,1-diphenyl-2-picrylhydrazyl, a radical scavenger, to decompose theperoxides), or the peroxidase method (reduction with glutathione,catalyzed by glutathione peroxidase, followed by measuring the coupledoxidation of NADPH in the presence of glutathione reductase). See, forexample, Fujimoto et al., Journal of Polymer Science Part A: PolymerChemistry, Vol. 31, 1035-1043 (1993).

In another embodiment, quantification and/or detection of the initiatorin the substrate pre-polymerization, or quantification and/or detectionof the initiator or its degradation product(s) in the substratepost-polymerization may be accomplished by extraction followed by any ofa range of analytical techniques. For example, quantifying and/ordetecting the amount of initiator or its degradation product(s) in theextract can be accomplished using spectroscopy and chromatography;including, UV/VIS, FTIR, nuclear magnetic spectroscopy, thin layerchromatography, gas chromatography, and liquid chromatography.

Monomers can be selected such that their reactivity ratios givealternating copolymers, periodic copolymers with a pre-specified ratioof each monomer, random copolymers, block copolymers or homopolymers.Inclusion of more than two reactive groups on each monomer unit allowsfor the formation of star polymers, dendrimers, regularly branchedpolymers, randomly branched polymers, and brush polymers. In general,the monomer may be selected from any of the monomers disclosed herein.Thus, for example, the monomers may contain any of the pendant groupscorresponding to Formulae ZI-1 to ZI-7. By way of further example, uponpolymerization the monomers may provide the polymer with repeat unitscorresponding to any of Formula 1-12. In a preferred embodiment, themonomers are miscible with the polymerization mixture solvent system.

In processes for modification of the surface of a hydrophobic substrate,a hydrophilic solvent system preferably is employed. Aqueous solutionspreferably are used as the solvent system, optionally containing ions orbuffers, such as sodium, ammonium, potassium, chloride, phosphate, oracetate. In processes for modifying hydrophilic substrates, ahydrophobic solvent system preferably is used. In such processes, thepreferred media is an organic solvent, typically a non-polar organicsolvent, or a mixture thereof. Exemplary organic solvents include one ormore of toluene, hexane, cyclohexane, benzene, xylene, tetrahydrofuran,and aliphatic alcohols. In a preferred embodiment, the solvent systemdoes not swell the substrate (or at least that portion of the substratefrom which the polymer will be grafted) by more than 25% by volume. Forexample, in one such embodiment, the solvent system does not swell thesubstrate (or at least that portion of the substrate from which thepolymer will be grafted) by more than 10% by volume. In a preferredembodiment, the solvent system does not swell the substrate (or at leastthat portion of the substrate from which the polymer will be grafted) bymore than 5% by volume. In one embodiment, the solvent system may evenshrink the substrate (or at least that portion of the substrate fromwhich the polymer will be grafted).

In one particularly preferred embodiment, the non-fouling polymericmaterials are grafted from the substrate by chain growth additionpolymerization. The polymerization conditions described herein aregenerally mild compared to other methods of polymerization and thus donot significantly alter the mechanical properties, flexibility, ordimensional properties of the underlying substrate. In one preferredembodiment, for example, polymerization is carried out at a temperaturenot in excess of 60° C. The polymerization may be carried out over arelatively wide pH range, e.g., about 0-10. In one embodiment, thepolymerization reaction is carried out at a pH of about 2-8. Forexample, when DCP and ferrous gluconate are used as redox pair, thepolymerization reaction may be carried out at a pH of about 6-8. By wayof further example, when benzoyl peroxide and ferrous gluconate are usedas redox pair, the polymerization reaction may be carried out at a pH ofabout 4-6. By way of further example, when O,O-t-Butyl-O-(2-ethylhexyl)mono-peroxycarbonate (“TBEC”) and ferrous gluconate are used as redoxpair, the polymerization reaction may be carried out at a pH of about5-7.

Examples of radical polymerization processes include, but are notlimited to, UV, thermal, and redox initiated processes. In particularembodiments, the polymer is grafted from the substrate, optionally byfirst imbibing with one or more monomers and/or initiators (such as anultraviolet (UV), thermal, or redox initiator) into the substrate andinitiating polymerization of one or more monomers from the surface. Inone embodiment, the initiator is incorporated into the substrate byimbibing the substrate with initiator or coating the substrate with alayer, e.g., an undercoating layer (sometimes referred to herein as theco-deposited layer), comprising the initiator. In another embodiment,the monomer is incorporated into the substrate by imbibing the substratewith monomer. The polymerization is typically initiated by exposing thesubstrate with a solution or suspension of the monomer or monomers to bepolymerized and an initiator. The quantity of polymer introduced to thesubstrate can be controlled by changing the concentration of the polymerin the solvent solution, surface tension of the polymer solution,polymerization temperature, pH of the polymer solution, polymerizationsolution agitation or flow conditions, by changing the amount of timethe substrate is allowed to be in the polymer solution during onepolymerization period, and/or by repeating any number of polymerizationperiods as required. When utilizing multiple polymerization periods, thepolymer(s) used in the subsequent polymerization periods can be the sameas, different from, or a mixture with the polymer(s) used in theprevious polymerization period.

Chain transfer agents can be added to the monomer solution to mediatethe graft-from radical polymerization reaction kinetics. Chain transferagents include, but are not limited to, molecules containinghalocarbons, thiols, dithiocarbamates, trithiocarbonates, dithioesters,xanthates, primary or secondary alcohols. Examples of chain transferagents are bromotrichloromethane, 4-methylbenzenethiol, benzyl alcohol,methanol, ethanol, ethyleneglycol, glycerol, and isopropanol. In oneembodiment the radical polymerization graftings are mediated using2,2,6,6-tetramethylpiperidinie-1-oxyl (TEMPO). In one embodiment theradical polymerization graftings are mediated using reversible additionfragmentation transfer (RAFT) agents. Examples of RAFT agents include2-(Dodecylthiocarbonothioylthio)-2-methylpropionic acid,2-Cyano-2-propyl benzodithioate, 2-Cyano-2-propyl dodecyltrithiocarbonate, 4-Cyano-4-(phenylcarbonothioylthio)pentanoic acid,4-Cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid,Bis(dodecylsulfanylthiocarbonyl) disulfide, Bis(thiobenzoyl) disulfide,Cyanomethyl dodecyl trithiocarbonate, Cyanomethylmethyl(phenyl)carbamodithioate, and their analogues and derivatives

Oxygen can act as an inhibitor in free radical polymerization as it canreact quickly with the free radicals generated by the initiator to formstable radical species, which in turn can react with other radicalspecies to form unreactive species which terminate the polymerization.Therefore, creating an oxygen-free environment by degassing withnitrogen or argon or vacuum is typically used to remove oxygen beforeand during polymerization. However, for certain embodiments, it wouldpreferable not to require such degassing steps in commercial production.In one preferred embodiment, the polymerization method is other thanATRP, which typically requires stringent control of oxygen levels thatmay be difficult to achieve during manufacturing.

Alternatively, oxygen in the system can be minimized by filling thereactor with the reaction mixtures thus physically displacing the oxygenin the reactor. In another embodiment, reagents which scavenge oxygencan be added to the reaction mixture. Suitable oxygen-scavengingreagents include, but are not limited to, sodium (meta) periodate,riboflavin, and ascorbic acid. These agents may improve the efficacy ofthe resulting polymer if the polymerization does not employ an inertatmosphere.

In addition to monomer and a solvent system, the polymerization mixturemay optionally contain a free radical inhibitor to encourage surfacegrafting. Without being bound to any particular theory, it is presentlybelieved that the addition of a free radical inhibitor, including,hydroquinone, hydroquinone monomethyl ether, phenothiazine,3,7-bis(dimethylamino)phenazathionium chloride, triethylene diamine,t-butylcatechol, butylated hydroxytoluene, and 4-t-butylphenol to thegrafting solution decreases solution polymerization, thereby allowingmore monomer to be available for grafting at or near the substratesurface/polymerization mixture interface.

Plasticizers can be incorporated into the grafted polymer at any timeduring and/or subsequent to surface polymerization. In the preferredembodiment, a hydrophilic plasticizer (such as citrated esters, ethyleneglycol, propylene glycol, and/or polyethylene glycol [<2000 M_(w)]) isincorporated into the grafted polymer in a post-polymerization aqueouswash period.

i. UV Initiators

In one embodiment, the initiator is an ultraviolet (UV) initiator. Thesubstrate and initiator are typically placed into an aqueous, degassed,solution containing a zwitterionic monomer and exposed to UV light,initiating the radical polymerization. Typically, the UV light has awavelength of from about 220-400 nm and an intensity of 100 W. Thedistance of the reaction solution can vary, for example, at distancesfrom about 2 cm to about 50 cm. The UV exposure time can also vary,e.g., from 30 seconds to about 4 hours. In one exemplary embodiment, theUV light has a peak wavelength of 365 nm, generated by a 100 W UV.

In accordance with one aspect of the disclosure, unreacted initiatorresidue in non-extracted lenses can be used to facilitate surfacemodification via UV reaction. Lenses polymerized via UV and/or visiblelight energy use compounds excitable with UV-visible light to generateradicals and initiate the curing polymerization process. Excessinitiator is preferably used to ensure adequate reaction; the excessinitiator residue can be later extracted from the lens before packagingand sterilization.

In one embodiment, the surface modification reaction is performed usingUV-initiated polymerization of the hydrophilic monomer to the surface ofthe contact lens, using only the residual initiator from the lensformation. Without the need to introduce other initiators, this methodconveniently fits within current contact lens manufacturing processes,reduces cost and chemical waste, and simplifies the surfacemodification. For example, the current process for manufacturing acontact lens may include extraction steps wherein the cured contact lensis exposed to aqueous solutions, solvents and/or alcohol to extract theresidual initiator and unreacted monomer. Without extracting theunreacted initiator, a separate reaction can be initiated usingUV-initiated polymerization after the hydrophilic monomer is added. Onesurface of the lens may be exposed solely to the UV by controlling thewavelength and intensity of the UV. This may produce a contact lens thathas been modified on only the inner or outer surface. Both surfaces mayalso be modified by this method. In another embodiment, the processcomprises manufacturing contact lenses from monomers consisting of:introducing the contact lens substrate monomers with a UV initiator intoa mold, polymerizing within a mold, adding monomers for surfacemodification, and continuing UV exposure without introducing newinitiator. In certain embodiments, a greater level of initiator is usedin the initial polymerization of the contact lens to allow for residualinitiator in the surface modification step. By way of example, aninitiator weight percent of at least about 1 ppm to about 50,000 ppm ofthe weight of the reaction mixture is present for the UV initiationstage. Different intensities and wavelengths of UV may be used for thepolymerization of the contact lens body and the surface modification.After the surface modification, the contact lens may be exposed to theextraction steps of the current process for manufacturing an unmodifiedcontact lens.

In an alternate embodiment, two separate UV initiators aresimultaneously introduced with the contact lens monomers in the firststage of the process. In another alternate embodiment, two separate UVinitiators are introduced, one during the first stage of the process(i.e., curing the lens) and another during the second stage of theprocess (i.e., applying the surface modification). In some of theseembodiments, these separate initiators are capable of being initiatedunder different conditions from each other, such as at uniquewavelengths. Stated differently, one type of initiator could beinitiated during the contact lens molding steps and the second type ofinitiator could be initiated during the surface modification step.Preferably in the embodiments and examples in this paragraph, the UVlight has a wavelength of from about 250-400 nm (e.g., 360 nm) and anintensity of 100 W, and the range of exposure is from about 15 minutesto about 2 hours (e.g., 30 minutes)

Representative UV radical initiators for use in the embodiments andexamples described herein include, but are not limited to,1-Hydroxycyclohexyl phenyl ketone, 2,2-Diethoxyacetophenone,2-Benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone,2-Hydroxy-2-methylpropiophenone,2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone,2-Methyl-4′-(methylthio)-2-morpholinopropiophenone,3′-Hydroxyacetophenone, 4′-Ethoxyacetophenone, 4′-Hydroxyacetophenone,4′-Phenoxyacetophenone, 4′-tert-Butyl-2′,6′-dimethylacetophenone,Diphenyl(2,4,6-trimethylbenzoyl)phosphineoxide/2-hydroxy-2-methylpropiophenone,2,2-Dimethoxy-2-phenylacetophenone, 4,4′-Dimethoxybenzoin,4,4′-Dimethylbenzil, Benzoin ethyl ether, Benzoin isobutyl ether,Benzoin methyl ether, Benzoin, 2-Methylbenzophenone,3,4-Dimethylbenzophenone, 3-Hydroxybenzophenone, 3-Methylbenzophenone,4,4′-Bis(diethylamino)benzophenone, 4,4′-Dihydroxybenzophenone,4,4′-Bis[2-(1-propenyl)phenoxy]benzophenone,4-(Diethylamino)benzophenone, 4-Benzoylbiphenyl, 4-Hydroxybenzophenone,4-Methylbenzophenone, Benzophenone-3,3′,4,4′-tetracarboxylicdianhydride, Benzophenone, Methyl benzoylformate, Michler's ketone,Sulfoniums, iodiums,2-(4-Methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,Diphenyliodonium p-toluenesulfonate,N-Hydroxy-5-norbornene-2,3-dicarboximide perfluoro-1-butanesulfonate,N-Hydroxynaphthalimide triflate, 2-tert-Butylanthraquinone,9,10-Phenanthrenequinone, Anthraquinone-2-sulfonic acid sodium saltmonohydrate, Camphorquinone, Diphenyl(2,4,6-trimethylbenzoyl)phosphineoxide, 10-Methylphenothiazine, thioxanthones, and IRGACURE 2959.

ii. Thermal Initiators

In another embodiment a heat activated (thermal) initiator is used, inplace of, or in addition to, the UV initiator described above, and thegraft-from polymerization is initiated by heating the aqueous monomersolution temperature to a desired temperature and holding thetemperature constant until the desired degree of polymerization isachieved.

Suitable thermal initiators include, but are not limited to, tert-Amylperoxybenzoate, 4,4-Azobis(4-cyanovaleric acid),2,2′-Azobis[(2-carboxyethyl)-2-methylpropionamidine],2,2′-Azobis(4-methoxy-2,3,-dimethylvaleronitrile),1,1′-Azobis(cyclohexanecarbonitrile), 2,2′-Azobisisobutyronitrile(AIBN), Benzoyl peroxide, 2,2-Bis(tert-butylperoxy)butane,1,1-Bis(tert-butylperoxy)cyclohexane,2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane,2,5-Bis(tert-Butylperoxy)-2,5-dimethyl-3-hexyne,Bis(1-(tert-butylperoxy)-1-methylethyl)benzene,1,1-Bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-Butylhydroperoxide, tert-Butyl peracetate, tert-Butyl peroxide, tert-Butylperoxybenzoate, tert-Butylperoxy isopropyl carbonate, Cumenehydroperoxide, Cyclohexanone peroxide, Dicumyl peroxide, Lauroylperoxide, 2,4-Pentanedione peroxide, Peracetic acid, and Potassiumpersulfate.

The temperature to which the solution is heated is dependent, amongother things, on the monomer and/or the initiator, and/or the substrate.Examples of thermal radical initiators include, but are not limited to,azo-compounds such as azobisisobutyronitrile (AIBN) and1,1′-Azobis(cyclohexanecarbonitrile) (ABCN). Preferable graftingtemperatures are near the 10 hour T1/2 of the initiator selected. Thegraft-from radical polymerization reaction can be thermally quenched byheating beyond the initiators half life.

iii. Redox Initiators

In another embodiment, a redox initiator system is used to initiatepolymerization from the surface of the substrate. The redox initiatorsystem typically includes a pair of initiators: an oxidant and areducing agent. The redox chemistry described herein can be modified toprepare non-fouling polymeric materials, for example, such aszwitterionic polymeric materials. Redox initiation is regarded as aone-electron transfer reaction to effectively generate free radicalsunder mild conditions. Suitable oxidants include, but are not limitedto, peroxide, hydroperoxide, persulfates, peroxycarbonates,peroxydisulfates, peroxydiphosphate, permanganate, salts of metals suchas Mn(III), Ce(IV), V(V), Co(III), Cr(VI) and Fe(III).

Suitable reducing agents include, but are not limited to, metal saltssuch as Fe(II), Cr(II), V(II), Ti(III), Cu(II), and Ag(I) salts, andoxyacids of sulfur, hydroxyacids, alcohols, thiols, ketones, aldehydes,amine, and amides. For example, in some embodiments, the reducing agentis an iron(II) salt, such as iron(II) L-ascorbate, ferrous sulfate,iron(II) acetate, iron(II) acetylacetonate, iron(II) ethylenediammoniumsulfate, iron(II) gluconate, iron(II) lactate, iron(II) oxalate, oriron(II) sulfate.

Polymerization can be initiated by radicals formed directly from theredox reaction and/or by macroradicals formed by the abstraction of ahydrogen atom from the substrate by the transient radicals formed duringthe redox reaction.

In one embodiment, the substrate is coated with a undercoating coatingand the non-fouling material is grafted from the undercoating layer byredox polymerization. The undercoating coating contains oxidants orreducing agents. In a preferred embodiment, the undercoating layercontains one or more reducing agents, such as acids, alcohol, thiols,ketones, aldehydes, amines and amides. An oxidant is used to react withone or more functional groups of the undercoating layer to form radicalswhich initiate the graft-from polymerization.

In a particular embodiment, the undercoating layer is a copolymer withpendant groups of aliphatic chains containing silanol and/or hydroxylgroups. Such materials can be used to form a undercoating layer onpolymeric substrates, such as polyurethane (PU). An oxidant, such as asalt of Ce(IV), reacts with the hydroxyl group under mild conditions toform hydroxyl radicals in the undercoating layer to grow thezwitterionic polymers.

In still another embodiment, a pair of peroxides and metal salts (suchas Fe(II) as used in the Fenton Reaction) is used in the redoxpolymerization to graft zwitterionic polymers from polymers. Peroxidesfor use in the redox polymerization include hydrogen peroxide, diacylperoxides, dialkyl peroxides, diperoxyketals, hydroperoxides, ketoneperoxides, peroxydicarbonates, and peroxyesters. Exemplary diacylperoxides include decanoyl peroxide, lauroyl peroxide, succinic acidperoxide, and benzoyl peroxide, Exemplary dialkyl peroxides includedicumyl peroxide, 2,5-di(t-butylperoxy)-2,5-dimethylhexane, t-butylcumyl peroxide, a,a′-bis(t-butylperoxy)diisopropylbenzene mixture ofisomers, di(t-amyl) peroxide, di(t-butyl) peroxide and2,5-di(t-butylperoxy)-2,5-dimethyl-3-hexyne. Exemplary diperoxyketalsinclude 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane,1,1-di(t-butylperoxy)cyclohexane, 1,1-di(t-amylperoxy)cyclohexane,n-butyl 4,4-di(t-butylperoxy)valerate, ethyl3,3-di-(t-amylperoxy)butanoate and ethyl 3,3-di-(t-butylperoxy)butyrate.Exemplary hydroperoxides include cumene hydroperoxide and t-butylhydroperoxide. Exemplary ketone peroxides include methyl ethyl ketoneperoxide mixture and 2,4-pentanedione peroxide. Exemplaryperoxydicarbonates include di(n-propyl)peroxydicarbonate,di(sec-butyl)peroxydicarbonate, and di(2-ethylhexyl)peroxydicarbonate.Exemplary peroxyesters include 3-hydroxy-1,1-dimethylbutylperoxyneodecanoate alpha-cumyl peroxyneodecanoate, t-amylperoxyneodecanoate, t-butyl peroxyneodecanoate, t-amyl peroxypivalate,t-butyl peroxypivalate,2,5-di(2-ethylhexanoylperoxy)-2,5-dimethylhexane, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethyl hexanoate, t-amyl peroxyacetate,t-butyl peroxyacetate, t-butyl peroxyacetate, t-butyl peroxybenzoate,OO-(t-amyl) O-(2-ethylhexyl) monoperoxycarbonate,OO-(t-butyl)-O-isopropyl monoperoxycarbonate,OO-(t-butyl)-O-(2-ethylhexyl) monoperoxycarbonate, polyetherpoly-t-butylperoxy carbonate, and t-butylperoxy-3,5,5-trimethylhexanoate.

In accordance with one suitable process, for example, a Fenton reactionis used to initiate the surface modification reaction. In oneembodiment, oxidation by a mixture of an iron(II) species and hydrogenperoxide is performed under mild conditions, for example, roomtemperature, in an aqueous solution, and relatively low concentrationsof hydrogen peroxide (e.g., less than in some commercially marketedcontact lens cleaning solutions). The surface modification initiated bythe Fenton reaction is fast and a simple, one-step reaction, and unlikeother initiator systems, residual initiator is non-toxic and easilyextracted as described elsewhere herein. In one particular embodiment,the iron(II) species is present in the reaction mixture at aconcentration of from about 0.1 mM to about 0.5 M (e.g., 0.5 mM, 10 mM,25 mM, 50 mM, 100 mM, or 250 mM). In these and other embodiments, theperoxide (e.g., hydrogen peroxide) is present at a concentration of fromabout 0.05% to about 10% of the reaction mixture. Suitable solvents andsolvent systems for the reaction mixture, as well as representativetemperatures for carrying out the reaction, are as described elsewhereherein.

In some embodiments, any of the aforementioned peroxides such as benzoylperoxide, lauroyl peroxide, hydrogen peroxide, or dicumyl peroxide canbe imbibed into the polymer such as silicone hydrogel by dipping thepolymer into a peroxide solution in an organic solvent for apredetermined period of time and dried. The peroxide containing polymeris put into a solution of monomer. The redox polymerization is initiatedby the addition of a reducing agent, for example salts of Fe(II), suchas Fe(II) chloride, Fe(II) sulfate, ammonium Fe(II) sulfate, or Fe(II)gluconate, at room temperature or elevated temperature, to the monomersolution.

For modifying the surface of an article and/or surface graftpolymerization, it has been found particularly useful to usehydrophobic-hydrophilic redox initiator pairs. For example, in oneembodiment the hydrophobic member of a hydrophobic-hydrophilic redoxinitiator pair is incorporated into a hydrophobic substrate aspreviously described. The substrate surface is then treated with anaqueous polymerization mixture containing monomers, typicallyhydrophilic monomers, and the hydrophilic member of the redox pair. Thismethod offers particular advantages when polymers are being grafted fromcomponents having exposed external and internal surfaces to be modified(such as catheters) and any substrate that cannot readily be exposed tolight. Additionally, such a system tends to minimize the extent of nongraft polymerization in the bulk polymerization mixture away from thepolymerization mixture/substrate surface interface.

In a preferred embodiment, the hydrophilic-hydrophobic redox pair is ahydrophobic oxidizing agent/hydrophilic reducing agent pair wherein (i)the hydrophobic oxidizing agent is tert-amyl peroxybenzoate,O,O-t-Butyl-O-(2-ethylhexyl) mono-peroxycarbonate, benzoyl peroxide,2,2-bis(tert-butylperoxy)butane, 1,1-bis(tert-butylperoxy)cyclohexane,2,5-bis(tert-butylperoxy)-2,5-dimethylhexane,2,5-Bis(tert-Butylperoxy)-2,5-dimethyl-3-hexyne,bis(1-(tert-butylperoxy)-1-methylethyl)benzene,1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butylhydroperoxide, tert-butyl peracetate, tert-butyl peroxide, tert-butylperoxybenzoate, tert-butylperoxy isopropyl carbonate, cumenehydroperoxide, cyclohexanone peroxide, dicumyl peroxide, lauroylperoxide, 2,4-pentanedione peroxide, 4,4-azobis(4-cyanovaleric acid), or1,1′-Azobis(cyclohexanecarbonitrile), 2,2′-Azobisisobutyronitrile (AIBN)and (ii) the hydrophilic reducing agent is Fe²⁺, Cr²⁺, V²⁺, Ti³⁺, Co²⁺,Cu⁺, or an amine; transition metal ion complexes, e.g., copper (II)acetylacetonate, HSO³⁻, SO₃ ²⁻, S₂O₃ ²⁻, or S₂O₅ ². Exemplarycombinations include any of the aforementioned peroxides and Fe²⁺. Insome preferred embodiments, benzoyl peroxide, dicumyl peroxide, orO,O-t-Butyl-O-(2-ethylhexyl) mono-peroxycarbonate are used incombination with Fe²⁺.

In an alternative embodiment, the hydrophilic-hydrophobic redox pair isa hydrophilic oxidizing agent/hydrophobic reducing agent pair wherein(i) the hydrophilic oxidizing agent is peracetic acid, a persulfate suchas potassium persulfate, Fe³⁺+, ClO³⁻, H₂O₂, Ce⁴⁺, V⁵⁺, Cr⁶⁺, or Mn³⁺,or their combinations; and (ii) the hydrophobic reducing agent is analcohol, carboxylic acid, amine, or a boronalkyl or their combinations.

In accordance with one suitable process, for example, potassiumpersulfate can be used to initiate the surface modification reaction,similar to the Fenton reaction protocol described above. Unlike manyredox reactions which require a redox pair, potassium persulfate alonecan efficiently initiate the one-step reaction in aqueous solution. Inone particular embodiment, potassium persulfate is present in thereaction mixture at a concentration of from about 0.1 mM to about 0.5 M(e.g., 0.5 mM, 10 mM, 25 mM, 50 mM, 100 mM, or 250 mM). Suitablesolvents and solvent systems for the reaction mixture, as well asrepresentative times and temperatures for carrying out the reaction, areas described elsewhere herein.

Other suitable redox systems include (1) organic-inorganic redox pairs,such as oxidation of an alcohol by Ce⁴⁺, V⁵⁺, Cr⁶⁺, Fe³⁺Mn³⁺; (2)monomers which can act as a component of the redox pair, such asthiosulfate plus acrylamide, thiosulfate plus methacrylic acid, andN,N-dimethylaniline plus methyl methacrylate, and (3) boronalkyl-oxygensystems.

In accordance with another suitable process, for example, redoxchemistry with initiation by Ce(IV), using hydroxyl functionality as apoint from which to graft from and anchor the surface modification tothe substrate. However, any silicone-based hydrogel contact lens, thatis, being composed of silicon (>5% of the non-aqueous phase) andpossessing an oxygen permeability, D_(k), higher than 50×10⁻¹¹(cm²/sec), can be modified with this chemistry, whether or not hydroxylmoieties are present on the substrate. In some embodiments, for example,the concentration of silicone in the substrate (e.g., a contact lens)will be at least 1 wt. %, at least 5%, at least 10%, at least 15%, atleast 20%, at least 25% or at least 30%. Typically in these embodiments,Ce(IV) concentration will be from about 1 mM to about 10 mM in anaqueous solution; in some embodiments, for example, the Ce(IV)concentration will be about 1 mM, about 2 mM, about 3 mM, about 4 mM,about 5 mM, about 6 mM, about 7 mM, about 8 mM, about 9 mM, or about 10mM. Suitable solvents and solvent systems for the reaction mixture, aswell as representative times and temperatures for carrying out thereaction, are as described elsewhere herein.

iv. Exemplary Initiators

Exemplary initiators include, but are not limited to, diacyl peroxidessuch as benzoyl peroxide, dichlorobenzoyl peroxide, dilauroyl peroxide,didecanoyl peroxide, diacetyl peroxide succinic acid peroxide,disuccinic peroxide and di(3,5,5-trimethylhexanoyl) peroxide. In apreferred embodiment, the diacyl peroxide is an aromatic diacylperoxide, such as benzoyl peroxide.

Other exemplary initiators include, but are not limited to,peroxydicarbonates such as diethyl peroxydicarbonate, di-n-butylperoxydicarbonate, diisobutyl peroxydicarbonate,di-4-tert-butylcyclohexyl peroxydicarbonate, di-sec-butylperoxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-n-propylperoxydicarbonate and diisopropyl peroxydicarbonate; peroxyesters, suchas t-butyl perneodecanoate, t-butyl and t-amyl peroxy 2-ethyl hexanoate,and t-butyl peroxybenzoate; monoperoxycarbonates based on t-butyl andt-amyl monoperoxy 2-ethylhexyl carbonates; persulfates, such aspotassium persulfate, ammonium persulfate, and sodium persulfate; cumenehydroxide, tert-butyl hydroperoxide, di(tert-amyl) peroxide, tert-butylperoxide, 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane,1,1-Bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane;1,1-Bis(tert-amylperoxy)cyclohexane,1,1-Bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane,1,1-Bis(tert-butylperoxy)cyclohexane, 2,2-Bis(tert-butylperoxy)butane,2,4-Pentanedione peroxide, 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane,2,5-Di(tert-butylperoxy)-2,5-dimethyl-3-hexyne, 2-Butanone peroxide,cumene hydroperoxide, di-tert-amyl peroxide, dicumyl peroxide, lauroylperoxide, tert-butyl peracetate, tert-butyl peroxide, tert-butylperoxybenzoate, tert-butylperoxy 2-ethylhexyl carbonate,tert-Butylperoxy isopropyl carbonate, 4-nitro-benzenecarboperoxoic acidt-butyl ester, cyclohexanone peroxide,[(methylperoxy)(diphenyl)methyl]benzene,bis(t-butylcyclohexyl)peroxydicarbonate, and 2,4,6-triphenylphenoxyldimer.

For articles (substrates) requiring coating on both internal andexternal surfaces, or even both convex and concave surfaces, additionalconsiderations may be considered for initiating polymerization. Thermalinitiators can be used; however, the elevated temperature typicallyrequired can adversely affect the substrate material. UV basedapproaches must be designed such that they can penetrate through thematerial or can be applied intralumenally from a fiber optic sourcethreaded into the lumen for lumen-containing articles or directed fromabove and/or beneath the article for articles such contact lenses. Thismay be achieved by selecting a photoactive initiator which is labile ata UV wavelength not absorbed by the substrate polymer. Generally, lowerwavelength UV irradiation is less absorbed and penetrates more readilythan higher wavelength UV.

In contrast, redox chemistries generally do not require a direct line ofsight to a light source to initiate polymerization since polymerizationis not initiated photolytically and therefore may be advantageous forcoating substrates that have one or more surfaces that are difficult toexpose to the UV source. Further, redox polymerization typically can bedone at low temperatures, for example less than 100° C., less than 80°C., less than 60° C., less than 55° C., less than 50° C., less than 45°C., less than 40° C., less than 35° C., or less than 30° C.

The graft-from polymerization can propagate through a cationic oranionic reaction, where the substrate surface acts as the cation oranion initiator or a cationic or anionic initiator is immobilized on thesubstrate and the monomer contains a reactive olefin. Examples ofanionic polymerization are anionic ring opening, as in the case ofsynthesizing polycaprolactone or polycaprolactam, where thepolymerization proceeds through a lactone or lactam moiety in a ringstructure containing a pendant zwitterion group. Alternatively, anorganic ring containing one or more units of unsaturation and a pendantzwitterionic group are polymerized. In one embodiment a pendant olefinis included in the monomer unit and is used for crosslinking, such as inring opening metathesis polymerization (ROMP).

Packaging and Storage Solutions

As an alternative to the methods described above for providing thesurface modification, a medical device such as a contact lens can besurface modified by immersing the device in a packaging or storagesolution containing the polymer or copolymers described hereinabove. Inone embodiment, the solution is a packaging solution for storing thelens. The packaging and storage solutions according to the presentdisclosure may be physiologically compatible, or may require the enduser to wash or rinse the lens and place it in a physiologicallycompatible storage solution. In one embodiment, for example, thesolution is “ophthalmically safe” for use with a lens such as a contactlens, meaning that a contact lens treated with the solution is generallysuitable and safe for direct placement on the eye without rinsing, thatis, the solution is safe and comfortable for daily contact with the eyevia a contact lens that has been wetted with the solution. Anophthalmically safe solution has a tonicity and pH that is compatiblewith the eye and includes materials, and amounts thereof, that arenon-cytotoxic according to ISO standards and U.S. Food & DrugAdministration (FDA) regulations. In another embodiment, the storage andpackaging solution is such that a lens stored therein requires washingor rinsing prior to placement in the eye. The polymer or copolymer willordinarily be present in the solution in an amount ranging from about 10ppm to about 10 wt. %, and preferably about 0.1 wt. % to about 5 wt. %.

The packaging or storage solution should also be sterile in that theabsence of microbial contaminants in the product prior to release mustbe statistically demonstrated to the degree necessary for such products.The liquid media useful in the present invention are selected to have nosubstantial detrimental effect on the lens being treated or cared forand to allow or even facilitate the present lens treatment ortreatments. The liquid media are preferably aqueous-based. Aparticularly useful aqueous liquid medium is that derived from saline,for example, a conventional saline solution or a conventional bufferedsaline solution.

The pH of the packaging or storage solutions should be maintained withinthe range of about 6 to about 9, and preferably about 6.5 to about 7.8.Suitable buffers may be added, such as boric acid, sodium borate,potassium citrate, citric acid, sodium bicarbonate, trimethamine, andvarious mixed phosphate buffers (including combinations of Na₂HPO₄,NaH₂PO₄ and KH₂PO₄) and mixtures thereof. Generally, buffers will beused in amounts ranging from about 0.05 to about 2.5 percent by weight,and preferably from about 0.1 to about 1.5 percent by weight of thesolution.

Typically, the solutions of the present invention are also adjusted withtonicity agents, to approximate the osmotic pressure of normal lacrimalfluids which is equivalent to a 0.9 percent solution of sodium chlorideor 2.5 percent of glycerol solution. The solutions are madesubstantially isotonic with physiological saline used alone or incombination, otherwise if simply blended with sterile water and madehypotonic or made hypertonic the lenses will lose their desirableoptical parameters. Correspondingly, excess saline may result in theformation of a hypertonic solution which will cause stinging and eyeirritation.

Examples of suitable tonicity adjusting agents include, but are notlimited to, sodium and potassium chloride, dextrose, glycerin, calciumand magnesium chloride and the like and mixtures thereof. These agentsare typically used individually in amounts ranging from about 0.01 toabout 2.5% w/v and preferably from about 0.2 to about 1.5% w/v.Preferably, the tonicity agent will be employed in an amount to providea final osmotic value of at least about 200 mOsm/kg, preferably fromabout 200 to about 400 mOsm/kg, more preferably from about 250 to about350 mOsm/kg, and most preferably from about 280 to about 320 mOsm/kg.

If desired, one or more additional components can be included in thepackaging or storage solution. Such additional component or componentsare chosen to impart or provide at least one beneficial or desiredproperty to the packaging or storage solution. Such additionalcomponents may be selected from components which are conventionally usedin one or more ophthalmic device care compositions. Examples of suchadditional components include cleaning agents, wetting agents, nutrientagents, sequestering agents, viscosity builders, contact lensconditioning agents, antioxidants, and the like and mixtures thereof.These additional components may each be included in the packaging orstorage solutions in an amount effective to impart or provide thebeneficial or desired property to the packaging or storage solutions.For example, such additional components may be included in the packagingor storage solutions in amounts similar to the amounts of suchcomponents used in other, e.g., conventional, contact lens careproducts.

Exemplary sequestering agents include, but are not limited to, disodiumethylene diamine tetraacetate, alkali metal hexametaphosphate, citricacid, sodium citrate and the like and mixtures thereof. Exemplaryviscosity builders include, but are not limited to, hydroxyethylcellulose, hydroxymethyl cellulose, polyvinyl pyrrolidone, polyvinylalcohol and the like and mixtures thereof. Exemplary antioxidantsinclude, but are not limited to, sodium metabisulfite, sodiumthiosulfate, N-acetylcysteine, butylated hydroxyanisole, butylatedhydroxytoluene and the like and mixtures thereof.

Kits and Methods of Packaging and Storing Articles

Another aspect of the present disclosure is directed to a method ofpackaging and storing a medical device as described herein, such as acontact lens. In one embodiment, the method includes at least packagingan contact lens as described herein immersed in an aqueous contact lenspackaging solution, for example a packaging and storage solution that iscapable of providing a surface modification as described herein. Themethod may include immersing the lens in an aqueous packaging solutionprior to delivery to the customer/wearer, directly following manufactureof the contact lens. Alternately, the packaging and storing in thesolution described above may occur at an intermediate point beforedelivery to the ultimate customer (wearer) but following manufacture andtransportation of the lens in a dry state, wherein the dry lens ishydrated by immersing the lens in the contact lens packaging solution.Consequently, a package for delivery to a customer may include a sealedcontainer containing one or more unused contact lenses immersed in anaqueous packaging and storage solution according to the presentdisclosure.

In one embodiment, the steps leading to the present ophthalmic lenspackaging system includes (1) molding an ophthalmic lens in a moldcomprising a posterior and anterior mold portion, (2) removing the lensfrom the mold and hydrating the lens, (3) introducing the packagingsolution with the surface modification polymer or copolymer into thecontainer with the lens supported therein, and (4) sealing thecontainer. Additional steps may include performing an imbibing stepand/or one or more surface modification steps as described herein. Forexample, step (3) above may involve applying a surface modification onthe hydrated lens in the packaging solution, e.g., by introducing one ormore monomer and initiator combinations and initiating polymerization asdescribed herein (e.g., such as an ultraviolet (UV), thermal, or redoxinitiated polymerization). Preferably, the method also includes the stepof sterilizing the contents of the container. Sterilization may takeplace prior to, or most conveniently after, sealing of the container andmay be effected by any suitable method known in the art, e.g., byautoclaving of the sealed container and its contents at temperatures ofabout 120° C. or higher.

In another embodiment, this invention comprises: (1) molding anophthalmic lens in a mold comprising a posterior and anterior moldportion, (2) removing the lens from the mold, and (3) introducing thelens and the solution with the surface modification polymer or copolymerinto a container.

Having described the invention in detail, it will be apparent thatmodifications and variations are possible without departing the scope ofthe invention defined in the appended claims. Furthermore, it should beappreciated that all examples in the present disclosure are provided asnon-limiting examples.

EXAMPLES

The following non-limiting examples are provided to further illustratethe present invention. It should be appreciated by those of skill in theart that the techniques disclosed in the examples that follow representapproaches the inventors have found function well in the practice of theinvention, and thus can be considered to constitute examples of modesfor its practice. However, those of skill in the art should, in light ofthe present disclosure, appreciate that many changes can be made in thespecific embodiments that are disclosed and still obtain a like orsimilar result without departing from the spirit and scope of theinvention.

Example 1

Grafting SBMA Polymer on Contact Lens Surface Via Ce(IV) MediatedReaction.

A contact lens was placed into a glass vial filled with an aqueoussolution of 5% (wt/wt) SBMA with 1 mM ammonium cerium (IV) nitrate. Thevial was topped off with the same reaction solution and was cappedwithout any air bubbles. After it was sealed with electric tape, thevial was put on a shaker at 100 rpm at 60° C. for 1 h. After reaction,the sample was taken out and rinsed with 0.15M NaCl overnight.

Example 2

Grafting SBMA Polymer on Contact Lens Surface Via UV Chemistry.

Step 1. Initiator IRGACURE 2959 imbibing. IRGACURE 2959 was dissolved inwater at 37° C. to make a 0.5% solution. Contact lenses were placed in a20 mL glass vial with 0.5% IRGACURE solution on a shaker at 100 rpm at37° C. for 1 h. After rinsing with water for about 30 seconds, thecontact lenses were put on a polyethylene rack to be separated from eachother. After the lenses were dried with small air flow, they were keptin the dark overnight for further drying.

Step 2. UV grafting. The IRGACURE 2959 imbibed contact lenses were putinto quartz glass tubes (one lens per tube) with 10% SBMA(wt) in waterstoppered with rubber septa and secured with parafilm. The SBMA solutionwas purged with nitrogen through needles for 20 min and the needles weretaken out. Any bubble attached on the contact lenses was removed bytapping the tubes. The tubes were placed upright in a UV-reactor andirradiated with spinning for 30 min. After removing the tubes from thereactor, each contact lens was rinsed in 0.15M NaCl overnight.

Example 3

Grafting pSBMA from Silicone Hydrogel Contact Lens Surfaces UsingTBEC-Fe(II) Initiated Redox Polymerization to Improve SurfaceHydrophilicity and Wettability.

A solution was prepared by adding t-butyl ethylhexyl peroxycarbonate(TBEC, a thermal initiator) (1.0 weight/volume %) to heptane. Fivesilicone hydrogel contact lenses were immersed in 50 ml of the abovesolution. The solution container was protected from light and thesolution was agitated using an orbital shaker set at 120 rpm for 30minutes. After 30 minutes, the above solution was decanted and thelenses were immersed and agitated in approximately 20 ml of heptane forapproximately 10 seconds to remove residual TBEC. The heptane wasdecanted and the lenses imbibed with TBEC were dried for approximately10 seconds on each side in a closeable rack using a gentle stream ofcompressed air. The lenses imbibed with TBEC were then protected fromthe light and allowed to dry at ambient conditions for 1-2 hours.

A solution was prepared by dissolvingN-(3-sulfopropyl)-N-methacryloxyethyl-N,N-dimethylammonium betaine(SBMA) in de-ionized water. A solution was prepared by dissolvingiron(II) gluconate dihydrate (ferrous gluconate) in de-ionized water.The aqueous ferrous gluconate solution was added to the aqueous SBMAsolution and mixed thoroughly to create the reaction solution (1.0, 5.0,or 10.0 weight % SBMA, 5 mM ferrous gluconate). The reaction solutionwas then added to reaction vessels, and the lenses that had beenpreviously imbibed with TBEC were immersed in the reaction solution. Allair bubbles were removed from the lenses and reaction solution was addeduntil the reaction vessel was completely full. The reaction vessel wascapped and secured with parafilm and vinyl electrical tape to create anair-tight seal. The solutions containing the lenses were agitated usingan orbital shaker set at 120 rpm and were heated at 60° C. for 2 hoursto induce thermal graft-polymerization from the lens surface. After the2 hour polymerization, the lenses were immersed in 0.15 M saline andagitated on an orbital shaker set at 120 rpm for 30 minutes to removeentangled oligomer, homopolymer and unreacted monomer from the lenssurface. This 30 minute rinsing procedure was repeated two more timesfollowed by an overnight rinse.

The contact angle of the surfaces of the treated lenses was measuredusing the static captive bubble method. Contact angle measurements forthe Control lenses ranged from 19° to 36° whereas contact anglemeasurements for the lenses treated according to the invention all hadcontact angle measurements of 0° wherein there was no interaction of thecaptive air bubble with the modified surfaces.

The data demonstrate that the method of this invention significantlyenhances the hydrophilicity and wettability of the surfaces of siliconehydrogel contact lenses.

Example 4 Adding Salt to Improve Processing

During the grafting of SBMA on contact lens via both Ce(IV) and UVchemistry, homopolymer of SBMA was produced during the reaction. Due tothe existence of UCST of SBMA homopolymer, it precipitated from thesolution when the reaction was not run at high temperature. As thehomopolymer is soluble in salt solution, the addition of salt reducedthe formation of precipitation during above reactions and kept to keep aclear solution. For example, 0.15M NaCl was added in Example 1 and 2.

Example 5 Process Description of UV in Various Manufacturing Processes(Without Initiators)

A non-extracted contact lens was put within the SBMA solution in aquartz glass tube. The SBMA solution was purged with nitrogen throughneedles for 20 min and the needles were taken out. Any bubble attachedon the contact lenses was removed by tapping the tubes. The tubes wereplaced upright in a UV-reactor and irradiated with spinning for 30 min(100 W, mercury lamp, wavelength ca 360 nm). After removing the tubesfrom the reactor, each contact lens was rinsed in 0.15M NaCl overnightand thereafter evaluated using ATR-FTIR and contact angle test.

Example 6 Grafting Betaine Polymers Using Other Initiators

A contact lens and a polyHEMA hydrogel were added into a glass vialfilled with the aqueous solution of 5% (wt/wt) SBMA with 1-5 mM iron(III) or other transitional or lanthanide metals. The vial was added tofull with the reaction solution and was capped without any air bubbles.After being sealed with electric tape, the vial was put on the shaker at100 rpm at 60° C. for 1 h. After reaction, the sample was taken out andrinsed with 0.15M NaCl overnight. Other initiators were tried and thereactions are listed in Table 1.

TABLE 1 New Catalysts for Polymerizing SBMA from Silicone HydrogelContact Lenses and from polyHEMA Hydrogel Evidence of Catalyst SBMAGrafting by Catalyst Conc. Substrate Conc. (%) ATR-FTIR Fenton's 1 mMH₂O₂ SiHy Contact 10 Yes Reagent 100 mM Lens Fe(II)- gluconate Fenton's1 mM H₂O₂ pHEMA 10 Yes Reagent 100 mM Hydrogel Fe(II)- gluconate

Example 7 Grafting Betaine Polymers Using Other Initiators

A contact lens and a polyHEMA hydrogel were added into a glass vialfilled with the aqueous solution of 5% (wt/wt) SBMA with 1-5 mMpotassium persulfate. The vial was added to full with the reactionsolution and was capped without any air bubbles. After being sealed withelectrical tape, the vial was put on the shaker at 100 rpm at 60° C. for1 h. After reaction, the sample was taken out and rinsed with 0.15M NaClovernight. Other initiators were tried and the reactions are listed inTable 2.

TABLE 2 New Catalysts for Polymerizing SBMA from Silicone HydrogelContact Lenses and from polyHEMA Hydrogel SBMA Evidence of CatalystConc. Grafting by Catalyst Conc. Substrate (%) ATR-FTIR PotassiumPersulfate 1 mM SiHy Contact 5 Yes Lens Potassium Persulfate 1 mM pHEMA5 Yes Hydrogel

Example 8 Grafting SBMA on Other Lenses from CIBA, Cooper, J&J, B&L, andContamac

The following lenses from different companies (all silicone-basedhydrogels) were modified using cerium and UV chemistry, grafting SBMA onthe surface. The surface was characterized with ATR-FTIR. Contact angleafter modification was measured.

Evi- dence of Grafting Static by Sam- Contact ATR- ple SubstrateChemistry Angle FTIR 1 ocufilcon D  5% SBMA + 1 mMCe(IV), 3 h 0° yes 2lotrafilcon B 10% SBMA + 2 mMCe(IV), 4 h 0° yes 3 lotrafilcon B 10%SBMA + 5 mMCe(IV), 4 h 0° yes 4 senofilcon A 10% SBMA + 1 mMCe(IV), 4 hN/A yes 5 senofilcon A 10% SBMA + 4 mMCe(IV), 4 h N/A yes 6 efrofilcon A 5% SBMA + 1 mMCe(IV), N/A yes 1.7 h 7 efrofilcon A  5% SBMA + 1mMCe(IV), N/A yes 1.7 h 8 ocufilcon D 10% SBMA, no initiator, 3 h 0° yes9 lotrafilcon B 10% SBMA, no initiator, 1 h N/A yes 10 etafilcon A 10%SBMA, no initiator, 3 h N/A yes 11 efrofilcon A 10% SBMA, no initiator,1.5 h N/A yes 12 efrofilcon A 10% SBMA, no initiator, 1.5 h N/A yes

Example 9

Multiple types of silicone hydrogel lenses were modified according tothe previous examples and analyzed using Eosin staining or EDS. Thesilicone hydrogel lenses, measurements reaction conditions areidentified in Table 1 and the results are depicted in FIGS. 1-4. FIG. 4shows measurement of atomic percentage on the y-axis proceeding from aposition outside the lens, through the surface of the lens (atapproximately 4 microns), and then into the depth of the lens beyond 4microns. These examples demonstrate the uniformity of the surfacemodification on each lens. These examples also demonstrate theflexibility of the chemistry and the ability to modify a variety oflenses with various depths of penetration based on the reactionconditions.

TABLE 1 Eosin Reaction Conditions images SiHy/TBEC 1% TBEC in heptane(30 min, FIG. 1 Eosin thickness: 5 μm; 22° C.), 1% SBMA, 5 mM Fe(II)total thickness: 153 μm; gluconate, 2 h, 60° C., autoclaved 3.3%penetration depth SiHy/Ce 5% SBMA, 1 mM Ce(IV), 60° C., FIG. 2 Eosinthickness: 4 μm; 1 h total thickness: 180 μm; 2.2% penetration depthSiHy/UV 0.5% initiator, 5 ml/lens imbibed 1 h FIG. 3 Eosin thickness: 7μm; at 37° C., rinse and dry, then 10% total thickness: 126 μm; SBMA,UV, 0.5 h 5.5% penetration depth SiHy/Ce 10% SBMA, 1.5 mM Ce(IV), 60°C., FIG. 4 EDS thickness: 3.5 μm 4 h

Example 10

Multiple batches of silicone hydrogel contact lenses (Air Optix® Aqualenses) were modified as described in Example 1 (except that the aqueoussolution was an aqueous solution of 15% (wt/wt) SBMA with 1 mM ammoniumcerium (IV) nitrate) and the vial was put on a shaker for 4 hours) andmeasured for Contact Angle and Dimensions. The average advancing contactangle was 19.3±2.4 degrees. The average dimensions were 14.2±0.04 mmdiameter and 8.53±0.05 mm base curve.

Example 11

Samples of modified contact lenses according to Example 10 weresubmitted for coefficient of friction measurements. Results demonstratedthat the modified lenses had 62% less friction than the unmodifiedcontrol lenses.

Example 12

Samples of modified contact lenses according to Example 10 weresubmitted for total sulfur analysis. The results were 0.078%.

Example 13

Samples of modified contact lenses according to Example 10 weresubmitted for oxygen permeability (Dk) measurements by a polarographicmethod. The results were that the effective permeability was 106 Fatt Dkunits compared to 110 Fatt Dk units for unmodified lenses. Thisdemonstrates that Dk, one of the bulk properties of the lenses, was notchanged substantially.

Example 14

Samples of modified contact lenses according to Example 10 weresubmitted for power measurements after storage at ambient temperaturefor 90 days. The results for the modified lenses were −0.53 Diopterscompared to −0.50 Diopters for the unmodified lenses, demonstrating thatthe power of the lenses was not changed substantially by modifying thesurface.

Example 15

Samples of modified contact lenses according to Example 10 weresubmitted for water content. The results were 36% water content for themodified lenses compared to 33% water content for unmodified controllenses. This demonstrates that the surface modification does notsubstantially change the bulk water content.

Example 16

Samples of modified contact lenses according to Example 10 weresubmitted for Zeta Potential. The results demonstrated a neutral chargefor both the modified and unmodified lenses, showing no change insurface charge due to the surface modification.

Example 17

Samples of modified contact lenses according to Example 10 weresterilized by autoclave and submitted for sterility testing. Resultsdemonstrated no growth of organisms over 2 weeks in soybean caseindigest broth (SCDB) or fluid thioglycollate medium (FTM). This resultindicates that the contact lenses were able to be sterilized and thechosen packaging was able to maintain the sterility of the lenses.

Example 18

Samples of modified contact lenses according to Example 10 were testedfor Endotoxin by LAL method. Results demonstrated the lenses had nodetectable endotoxins (<0.025 Endotoxin Units per device).

Example 19

Samples of modified contact lenses according to Example 10 weresubmitted for Biocompatibility testing. The results demonstrated thatthe lenses were not cytotoxic per ISO 10993-5, not irritating to oculartissue per ISO 10993-10 and there was no evidence of systemic toxicityper ISO 10993-11.

Example 20

Samples of modified contact lenses were subjected to a simulatedcleaning regimen for 30 cycles. Lenses were rinsed with a 3% hydrogenperoxide solution and rubbed between gloved palm and index finger for 30seconds. This stress was performed 30 times consecutively to simulateone month of cleaning. Advancing contact angles for the modified lensesafter rubbing were 17±2 degrees, whereas the average advancing contactangle for the control lenses increased to above 30 degrees.

Example 21

Samples of modified contact lenses according to Example 10 were testedin 10 patients for evaluation of safety under an IRB approved protocol.No safety concerns were noted.

Example 22

A modified contact lens prepared according to Example 10 and anotherwise identical contact lens that was not modified according toExample 10 were analyzed on a Thermo Scientific K-Alpha XPS using amonochromatic soft aluminum K-alpha X-ray generated by 12 kV electronbeam, using X-ray energy of 1.4866 keV, line width of 0.85 eV, and spotsize of 400 micron. No carbon or other sputter-coating was used. Tostudy the depth profile, each of the samples were etched with an argonsputtering gun. The argon ions had an energy of 1000 eV. The raster sizewas 2 mm. Each etching cycle was 30 seconds. A survey spectrum wasscanned after each etching, so that the surface elements could bedetected and quantified. For the modified sample, 60 etching cycles wereperformed. For the unmodified control sample, 30 cycles were performed.

The results are depicted in FIGS. 5 and 6. In each of these, theconcentration of the element was normalized as a ratio (X:B) where “X”is the measured value at the point of measurement and “B” is the bulkconcentration where the concentration is not substantially changing. Inthese measurements, the bulk concentration “B” was determined bycalculating the average concentration over consecutive 50 nm intervalsand identifying the first interval where the average concentration iswithin 10% of the average concentration of the previous interval. InFIGS. 5 and 6, the concentrations are averaged over 50 nm intervals, andthe concentration is plotted at the leftmost point of the interval(e.g., the concentration plotted at 100 nm is the average ofconcentration from 100 nm to 150 nm).

For the unmodified sample, there was a 30% lower concentration ofsilicon on the surface than in the bulk (ratio of 0.7). For the modifiedsample the normalized ratio of the concentration of sulfur on thesurface was initially 10-fold greater than the concentration of sulfurin the bulk (after 200 nm) and decreased approximately linearly from 10to 1 over 200 nm whereas the normalized ratio of silicon increased from0.04 on the surface to 1. (See FIG. 5).

FIG. 6 is an analysis of the quaternary amine (N1s) within the top 250nm of the modified surface. The maximum normalized ratio for quaternaryamine N1s is about 50 (i.e., about 5-fold greater than the maximumnormalized ratio for sulfur) but the N1s normalized ratio curve has aslope and gradient that is consistent with slope and gradient of thenormalized ratio curve for sulfur for the surface modification.

What is claimed is:
 1. A process for modifying the surface of asilicon-containing hydrogel, the process comprising the steps of:imbibing a zwitterionic monomer into the silicon-containing hydrogel inan imbibing mixture comprising the silicon-containing hydrogel, thezwitterionic monomer and a solvent system; wherein the imbibing absorbsthe monomer into the hydrogel; and polymerizing the zwitterionic monomerto modify the surface of the silicon-containing polymer with azwitterionic polymer in a polymerization reaction mixture, thepolymerization reaction mixture comprising the imbibedsilicon-containing hydrogel, a solvent system, the zwitterionic monomerand a free radical initiator, the polymerization reaction mixture havinga composition that differs from the composition of the imbibing mixture.2. The process of claim 1 wherein the imbibing mixture further comprisesa hydrophilic free radical initiator.
 3. The process of claim 1 whereinthe imbibing mixture comprises the hydrophilic free radical initiatorand the zwitterionic monomer, and the imbibing mixture andpolymerization reaction comprise different solvent systems.
 4. Theprocess of claim 1 wherein the silicon-containing hydrogel contains atleast 1 wt. % silicon.
 5. The process of claim 1 wherein thesilicon-containing hydrogel contains at least 20 wt. % silicon.
 6. Theprocess of claim 1 wherein the zwitterionic polymer comprises acarboxyammonium polymer or a sulfoammonium polymer.
 7. The process ofclaim 1 wherein the zwitterionic polymer comprises a carboxybetainepolymer or a sulfobetaine polymer.
 8. The process of claim 1 wherein thezwitterionic polymer comprises at least one repeat unit corresponding toFormula 2:

wherein X³ is hydrogen, alkyl or substituted alkyl, and X⁴ is a pendantgroup comprising an oxylated alkylene moiety, a zwitterionic moiety, ananionic moiety, or a cationic moiety.
 9. The process of claim 8 whereinX³ is hydrogen or alkyl.
 10. The process of claim 8 wherein the repeatunit of Formula 2 is a zwitterionic repeat unit comprising azwitterionic moiety corresponding to Formula ZI-1, ZI-2, ZI-3, ZI-4,ZI-5, ZI-6A, ZI-6B, or ZI-7;

wherein T¹ and T² are independently oxygen, sulfur, NH or a bond, T³ ishydrocarbylene, substituted hydrocarbylene, ether, or oxylated alkylene,Z¹ is a moiety comprising a quaternary nitrogen, phosphonium orsulfonium cationic group, and * designates the point of covalentattachment, direct or indirect, of the zwitterion of Formula ZI-1 to thepolymer backbone;

wherein * designates the point of covalent attachment of the zwitterionof Formula ZI-2 to the polymer backbone, T³ is hydrocarbylene,substituted hydrocarbylene, or oxylated alkylene, and T⁴, T⁵ and T⁶ areindependently hydrogen, hydrocarbyl, substituted hydrocarbyl orheterocyclo;

wherein T⁸ is a bond, hydrocarbylene, substituted hydrocarbylene,heterocyclo, or in combination with T⁹ and T¹⁰ and the nitrogen atom towhich they are attached form a nitrogen-containing heteroaromatic ring,T⁹ and T¹⁰ are independently hydrogen, hydrocarbyl, substitutedhydrocarbyl or heterocyclo, or, T⁹ and T¹⁰, in combination with T⁸ andthe nitrogen atom to which they are attached form a nitrogen-containingheteroaromatic ring, T¹¹ is hydrocarbylene, substituted hydrocarbylene,ether, or oxylated alkylene, Z³ is carboxylate, phosphate, phosphonic,phosphonate, sulfate, sulfinic, or sulfonate, and * designates the pointof covalent attachment, direct or indirect, of the zwitterion of FormulaZI-3 to the polymer backbone;

wherein * designates the point of covalent attachment, direct orindirect, of the zwitterion of Formula ZI-4 to the polymer backbone; T¹²is a bond or —(CH₂)_(m)—with m being 1 to 3; T¹³ and T¹⁴ areindependently hydrogen, alkyl, or substituted alkyl; T¹⁵ is optionallysubstituted alkylene, phenylene, ether, or oxylated alkylene; and Z⁴ iscarboxylate or sulfate;

wherein * designates the point of covalent attachment, direct orindirect, of the zwitterion of Formula ZI-5 to the polymer backbone; HETis a heterocycle containing a quaternary nitrogen atom, T¹⁵ isoptionally substituted alkylene, phenylene, ether, or oxylated alkylene;and Z⁴ is carboxylate or sulfate;

wherein * designates the point of covalent attachment, direct orindirect, of the zwitterion of Formulae ZI-6A and ZI-6B to the polymerbackbone; T¹⁵ is optionally substituted alkylene, phenylene, ether, oroxylated alkylene; and Z⁴ is carboxylate or sulfate;

wherein T⁴, T⁵ and T⁶ are independently hydrogen, hydrocarbyl,substituted hydrocarbyl or heterocyclo; T¹² is a bond, hydrocarbylene,substituted hydrocarbylene, or heterocyclo, and * designates the pointof covalent attachment, direct or indirect, of the zwitterion of FormulaZI-7 to the polymer backbone.
 11. The process of claim 1 wherein thezwitterionic polymer comprises repeat units corresponding to Formula 3:

wherein X⁴⁴ comprises an oxylated alkylene moiety, a zwitterionicmoiety, an anionic moiety, or a cationic moiety.
 12. The process ofclaim 11 wherein _(X) 44 is —OX⁴⁵, —NHX⁴⁵, or —SX⁴⁵, and X⁴⁵ is asubstituted hydrocarbyl or heterocyclo moiety comprising an oxylatedalkylene moiety, a zwitterionic moiety, an anionic moiety, or a cationicmoiety.
 13. The process of claim 11 wherein X⁴⁴ is—O(CH₂)₂N⁺(CH₃)₂(CH₂)_(n)SO₃ ⁻, —O(CH₂)₂N⁺(CH₃)₂(CH₂)_(n)CO₂ ⁻,—NH(CH₂)₃N⁺(CH₃)₂(CH₂)_(n)CO₂ ⁻, or —NH(CH₂)₃N⁺(CH₃)₂(CH₂)_(n)SO₃ ⁻, andn is 1-8.
 14. The process of claim 11 wherein X⁴⁴ is—NH(CH₂)_(m)N(CH₂)_(n)CH₃(CH₂)_(p)SO₃,—NH(CH₂)_(m)N(CH₂)_(n)CH₃(CH₂)_(p)CO₂,—NH(CH₂)_(m)N⁺[(CH₂)_(n)CH₃]₂(CH₂)_(p)SO₃, —NH(CH₂) N⁺[(CH₂)_(n)CH₃]₂(CH₂)_(p)CO₂, —NH(CH₂)_(m)Ncyclo-(CH₂)_(p)CO₂, or—NH(CH₂)_(m)Ncyclo-(CH₂)_(p)SO₃, Ncyclo- is a heterocyclic structure ora heterocyclic derivative containing at least one nitrogen atom, m is1-8; n is 0-5; and p is 1-8.
 15. The process of claim 11 wherein X⁴⁴ is—O(CH₂)_(m)N(CH₂)_(n)CH₃(CH₂)_(p)SO₃,—O(CH₂)_(m)N(CH₂)_(n)CH₃(CH₂)_(p)CO₂,—O(CH₂)_(m)N⁺[(CH₂)_(n)CH₃]₂(CH₂)_(p)SO₃, —O(CH₂)N⁺[(CH₂)_(n)CH₃]₂(CH₂)_(p)CO₂, —O(CH₂)_(m)Ncyclo-(CH₂)_(p)CO₂, or—O(CH₂)_(m)Ncyclo-(CH₂)_(p)SO₃, Ncyclo- is a heterocyclic structure or aheterocyclic derivative containing at least one nitrogen atom, m is 1-8;n is 0-5; and p is 1-8.
 16. The process of claim 11 wherein X⁴⁴ is—O(CH₂)₂N⁺(CH₃)₂(CH₂)₃SO₃, —O(CH₂)₂N⁺(CH₃)₂(CH₂)₂CO₂,—NH(CH₂)₂N⁺(CH₃)₂(CH₂)₃SO₃, —NH(CH₂)₂N⁺(CH₃)₂(CH₂)₂CO₂,—NH(CH₂)₃N⁺(CH₃)₂(CH₂)₃SO₃, —NH(CH₂)₃N⁺(CH₃)₂(CH₂)₂CO₂,—O(CH₂)₂N⁺(CH₂CH₃)₂(CH₂)₃SO₃, —O(CH₂)₂N⁺(CH₂CH₃)₂(CH₂)₂CO₂,—O(CH₂)₂N⁺(CH₂CH₂CH₂CH₃)₂(CH₂)₃SO₃, —O(CH₂)₂N⁺(CH₂CH₂CH₂CH₃)₂(CH₂)₂CO₂or —NH(CH₂)₃Ncyclo-(CH₂)₃SO₃ and Ncyclo- is a heterocyclic structure ora heterocyclic derivative containing at least one nitrogen atom.
 17. Anarticle formed by the process of claim
 1. 18. The article of claim 17wherein the article is a contact lens.